# TTL triggers method 2

**URL:** <https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577>\
**Category:** Uncategorized\
**Created:** [September 30, 2016, 8:19pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577 "2016-09-30T20:19:52Z")\
**Posts on this page:** 18\
**Page:** 1

<div class="post-metadata">

**Author:** ![folsteinlab](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@folsteinlab](https://psychtoolbox.discourse.group/u/folsteinlab)\
**Post date:** [September 30, 2016, 8:19pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/1 "2016-09-30T20:19:52Z")

</div>

Hi all. I need to send TTL triggers from Ubuntu 14.04 LTS. Normally I use pp.m but our current solution uses Octave instead of Matlab and I can't get the mex file to compile. So I want to try the mysterious "method 2". But I cannot find the file LinuxParportServer.zip Could someone please send it or send a link to it?  
  

Advice on compiling ppmex.c on Octave would also be helpful. Here's the list of errors I got.  
  
mex -g -v ppmex.c  
ppmex.c: In function ‘getBit’:  
ppmex.c:75:13: error: ‘true’ undeclared (first use in this function)  
 return (true && (b & 1\<\<n)); /\* need a bona fide bool \*/  
 ^  
ppmex.c:75:13: note: each undeclared identifier is reported only once for each function it appears in  
ppmex.c: In function ‘printBits’:  
ppmex.c:81:9: warning: incompatible implicit declaration of built-in function ‘printf’ [enabled by default]  
 printf("%c",getBit(b,i) ? '1' : '0');  
 ^  
ppmex.c: In function ‘ppd’:  
ppmex.c:95:9: warning: incompatible implicit declaration of built-in function ‘printf’ [enabled by default]  
 printf("PPD ioctl %d: %d (%s)\n",action,result,strerror(errno));  
 ^  
ppmex.c: At top level:  
ppmex.c:100:1: error: unknown type name ‘uint64\_t’  
 void read(const uint64\_T reg, void \* const b, const int parportfd, const int reader, const int o) {  
 ^  
ppmex.c: In function ‘read’:  
ppmex.c:53:19: error: expected ‘(’ before ‘false’  
 #define USE\_PPDEV false /\* just sketched in atm \*/  
 ^  
ppmex.c:101:8: note: in expansion of macro ‘USE\_PPDEV’  
 if USE\_PPDEV {  
 ^  
ppmex.c:53:19: error: ‘false’ undeclared (first use in this function)  
 #define USE\_PPDEV false /\* just sketched in atm \*/  
 ^  
ppmex.c:101:8: note: in expansion of macro ‘USE\_PPDEV’  
 if USE\_PPDEV {  
 ^  
ppmex.c: At top level:  
ppmex.c:115:9: error: unknown type name ‘uint8\_t’  
 const uint8\_T \* const data,  
 ^  
ppmex.c: In function ‘doPort’:  
ppmex.c:119:25: error: ‘false’ undeclared (first use in this function)  
 static bool setup = false;  
 ^  
In file included from ppmex.c:30:0:  
/usr/include/octave-3.8.1/octave/mex.h:112:18: error: unknown type name ‘uint64\_t’  
 #define uint64\_T uint64\_t  
 ^  
ppmex.c:121:5: note: in expansion of macro ‘uint64\_T’  
 uint64\_T reg;  
 ^  
ppmex.c:53:19: error: expected ‘(’ before ‘false’  
 #define USE\_PPDEV false /\* just sketched in atm \*/  
 ^  
ppmex.c:125:8: note: in expansion of macro ‘USE\_PPDEV’  
 if USE\_PPDEV {  
 ^  
In file included from ppmex.c:30:0:  
ppmex.c: In function ‘mexFunction’:  
/usr/include/octave-3.8.1/octave/mex.h:112:18: error: unknown type name ‘uint64\_t’  
 #define uint64\_T uint64\_t  
 ^  
ppmex.c:265:5: note: in expansion of macro ‘uint64\_T’  
 uint64\_T \*addresses;  
 ^  
/usr/include/octave-3.8.1/octave/mex.h:160:17: error: unknown type name ‘uint8\_t’  
 #define uint8\_T uint8\_t  
 ^  
ppmex.c:266:5: note: in expansion of macro ‘uint8\_T’  
 uint8\_T \*data;  
 ^  
/usr/include/octave-3.8.1/octave/mex.h:112:18: error: unknown type name ‘uint64\_t’  
 #define uint64\_T uint64\_t  
 ^  
ppmex.c:269:5: note: in expansion of macro ‘uint64\_T’  
 uint64\_T address, port;  
 ^  
/usr/include/octave-3.8.1/octave/mex.h:160:17: error: unknown type name ‘uint8\_t’  
 #define uint8\_T uint8\_t  
 ^  
ppmex.c:270:5: note: in expansion of macro ‘uint8\_T’  
 uint8\_T bitNum, regOffset, value = 0;  
 ^  
ppmex.c:305:23: error: ‘false’ undeclared (first use in this function)  
 writing = false;  
 ^  
ppmex.c:308:23: error: ‘true’ undeclared (first use in this function)  
 writing = true;  
 ^  
ppmex.c:51:15: error: expected ‘(’ before ‘true’  
 #define DEBUG true  
 ^  
ppmex.c:315:8: note: in expansion of macro ‘DEBUG’  
 if DEBUG printf("%d lhs\n",nlhs);  
 ^  
ppmex.c:51:15: error: expected ‘(’ before ‘true’  
 #define DEBUG true  
 ^  
ppmex.c:335:8: note: in expansion of macro ‘DEBUG’  
 if DEBUG printf("\n\ndata:\n");  
 ^  
ppmex.c:51:15: error: expected ‘(’ before ‘true’  
 #define DEBUG true  
 ^  
ppmex.c:344:12: note: in expansion of macro ‘DEBUG’  
 if DEBUG {  
 ^  
ppmex.c:51:15: error: expected ‘(’ before ‘true’  
 #define DEBUG true  
 ^  
ppmex.c:359:8: note: in expansion of macro ‘DEBUG’  
 if DEBUG {  
 ^  
g++: error: ppmex.o: No such file or directory  
gcc -c -D\_FORTIFY\_SOURCE=2 -fPIC -I/usr/include/octave-3.8.1/octave/.. -I/usr/include/octave-3.8.1/octave -g -O2 -fstack-protector--param=ssp-buffer-size=4 -Wformat -Werror=format-security -pthread -fopenmp -g -I. ppmex.c -o ppmex.o  
g++ -shared -Wl,-Bsymbolic -o ppmex.mex ppmex.o -L/usr/lib/x86\_64-linux-gnu/octave/3.8.1 -L/usr/lib/x86\_64-linux-gnu -loctinterp -loctave -Wl,-Bsymbolic-functions -Wl,-z,relro  

 
  

with kind regards,  
  

Jonathan  

  
--   

Jonathan Folstein  
Assistant Professor  
Department of Psychology  
Florida State University   
1107 W. Call St.   
Tallahassee, FL 32306-4301
office: 850-645-0654  

fax: 850-644-7739
[folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 1, 2016, 5:36pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/2 "2016-10-01T17:36:08Z")

</div>

This one...  
  
[https://github.com/widmann/ppdev-mex](https://github.com/widmann/ppdev-mex)  
  
... can only send TTL triggers over parallel port, but is reported to work very well under Octave. Had a query and success feedback for this just about a month ago.  
  
Hope it helps,  
-mario

---

<div class="post-metadata">

**Author:** ![andreaswidmann](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@andreaswidmann](https://psychtoolbox.discourse.group/u/andreaswidmann)\
**Post date:** [October 1, 2016, 7:56pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/3 "2016-10-01T19:56:54Z")

</div>

Mario was faster. Yes, ppdev-mex should compile under Octave (tested with Octave 4 on Ubuntu 16.04) and there is an Octave 64bit mex binary.  
  
Best,  
Andreas  
  

> \> Am 01.10.2016 um 19:36 schrieb [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\>:  
> \>   
> \>   
> \>   
> \> This one...  
> \>   
> \> [https://github.com/widmann/ppdev-mex](https://github.com/widmann/ppdev-mex)  
> \>   
> \> ... can only send TTL triggers over parallel port, but is reported to work very well under Octave. Had a query and success feedback for this just about a month ago.  
> \>   
> \> Hope it helps,  
> \> -mario   
> \>   
> \>

---

<div class="post-metadata">

**Author:** ![folsteinlab](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@folsteinlab](https://psychtoolbox.discourse.group/u/folsteinlab)\
**Post date:** [October 7, 2016, 6:44pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/4 "2016-10-07T18:44:25Z")

</div>

Hi all, just got around to testing this. It almost worked. I am using Octave 3.8.1 on Ubuntu 14.04 LTS.   
  

1) I compiled the ppdev\_mex.c by typing "mex ppdev\_mex.c", producing ppdev\_mex.mex  

2) opened octave as superuser from the terminal  

2) I ran the following simple script under various configurations described below:  
  
  
addpath('/home/vpixx/Desktop/Experiments/ppdev-mex-master');  
  
pportaddress = 1  
disp('setaddress');  
%ppdev\_mex('Open');  
ppdev\_mex('Open', pportaddress);  
disp('opened port');  
more off  
for i = 1:3  
  
%pportaddress = i-1;  
%ppdev\_mex('Open', pportaddress);  
  
bitarray = ppdev\_mex('Write', pportaddress, 100);  
bitarray  
WaitSecs(0.001);  
ppdev\_mex('Write', pportaddress, 0);  
disp('sent a stim ttl');   
  
WaitSecs(.5);  
  
  
end  
ppdev\_mex('Close', pportaddress);  
  
  

Configuration 1: instead of the compiled mexfile, I used the included ppdevmex.mexa64. Under this the script runs, but bitarray is empty and no eventcodes show up in EEGlab.  
  

Configuration 2: Use the mexfile I compiled myself. The script freezes at the ppdev\_mex('Open', pportaddress);  
  

If I run the script as a normal user, I can get it to tell me "permission denied" for opening the parallel port:  
/dev/parport0 Permission denied  
error: ppdev\_mex: couldn't access port  
  
  

If I give it the wrong address (2) I get   
  
/dev/parport1 No such file or directory  
error: ppdev\_mex: couldn't access port  

  
  

So it seems to be working basically right, but it is failing somewhere inside of opening the port.   
  

I'll probably switch to matlab now and see if I can get it to work that way, but I just wanted to give you feedback for this particular Octave/Ubuntu combination. Any advice would of course be welcome but thanks for this updated code in any case. I'll see if it works in matlab.  
  

with kind regards,  
  

Jonathan  

  
  
  

  

> On Sat, Oct 1, 2016 at 3:56 PM, Andreas Widmann [widmann@...](mailto:widmann@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> 
> > Mario was faster. Yes, ppdev-mex should compile under Octave (tested with Octave 4 on Ubuntu 16.04) and there is an Octave 64bit mex binary.  
> >   
> > Best,  
> > Andreas  
> >    
> > \> Am 01.10.2016 um 19:36 schrieb [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> :  
> > \>   
> > \>   
> > \>   
> > \> This one...  
> > \>   
> > \> [https://github.com/widmann/ppd ev-mex](https://github.com/widmann/ppdev-mex)  
> > \>   
> > \> ... can only send TTL triggers over parallel port, but is reported to work very well under Octave. Had a query and success feedback for this just about a month ago.  
> > \>   
> > \> Hope it helps,  
> > \> -mario   
> > \>   
> > \>
> 
>   
>   
>   
> --   
> 
> Jonathan Folstein  
> Assistant Professor  
> Department of Psychology  
> Florida State University   
> 1107 W. Call St.   
> Tallahassee, FL 32306-4301
> office: 850-645-0654  
> 
> fax: 850-644-7739
> [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![andreaswidmann](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@andreaswidmann](https://psychtoolbox.discourse.group/u/andreaswidmann)\
**Post date:** [October 7, 2016, 9:26pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/5 "2016-10-07T21:26:11Z")

</div>

Hi,  
  
several points/issues:  
  
(1) mexa64 is a MATLAB binary. Please try/use the octave binary in the Octave3LinuxFiles64 subdir:  
[https://github.com/widmann/ppdev-mex/blob/master/Octave3LinuxFiles64/ppdev\_mex.mex?raw=true](https://github.com/widmann/ppdev-mex/blob/master/Octave3LinuxFiles64/ppdev_mex.mex?raw=true)  
  
(2) Please confirm that you followed the instructions given in the ppdev\_mex.m help text (Note section).  
[https://github.com/widmann/ppdev-mex/blob/master/ppdev\_mex.m](https://github.com/widmann/ppdev-mex/blob/master/ppdev_mex.m)  
In particular please reconfirm that the lp module is NOT loaded as it will block the port. You may post the output of the lsmod command (from terminal). You will also find instructions there how to get rid of the need of superuser privileges.  
  
(3) Please check/post the specifications of your EEG system. Not all EEG systems work with 1ms triggers. Some need trigger durations \>= sampling rate.  
  
(4) In case all that really doesn’t help I would suggest to first manually confirm with a multimeter that port status (pin 2-9 against GND 18-25, IIRC) doesn’t change by:  
ppdev\_mex('Write', pportaddress, 255)  
ppdev\_mex('Write', pportaddress, 0)  
respectively.  
  
And I do not remember having ever checked the bitarray output after making the changes for Octave compatibility (as we never use it). I have to confirm in the lab on Monday that the expected value/output is indeed returned.  
  
Hope this helps,  
Andreas  
  

> \> Am 07.10.2016 um 20:44 schrieb Jonathan Folstein [jonathan.r.folstein@...](mailto:jonathan.r.folstein@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\>:  
> \>   
> \>   
> \>   
> \> Hi all, just got around to testing this. It almost worked. I am using Octave 3.8.1 on Ubuntu 14.04 LTS.   
> \>   
> \> 1) I compiled the ppdev\_mex.c by typing "mex ppdev\_mex.c", producing ppdev\_mex.mex  
> \> 2) opened octave as superuser from the terminal  
> \> 2) I ran the following simple script under various configurations described below:  
> \>   
> \>   
> \> addpath('/home/vpixx/Desktop/Experiments/ppdev-mex-master');  
> \>   
> \> pportaddress = 1  
> \> disp('setaddress');  
> \> %ppdev\_mex('Open');  
> \> ppdev\_mex('Open', pportaddress);  
> \> disp('opened port');  
> \> more off  
> \> for i = 1:3  
> \>   
> \> %pportaddress = i-1;  
> \> %ppdev\_mex('Open', pportaddress);  
> \>   
> \> bitarray = ppdev\_mex('Write', pportaddress, 100);  
> \> bitarray  
> \> WaitSecs(0.001);  
> \> ppdev\_mex('Write', pportaddress, 0);  
> \> disp('sent a stim ttl');   
> \>   
> \> WaitSecs(.5);  
> \>   
> \>   
> \> end  
> \> ppdev\_mex('Close', pportaddress);  
> \>   
> \>   
> \> Configuration 1: instead of the compiled mexfile, I used the included ppdevmex.mexa64. Under this the script runs, but bitarray is empty and no eventcodes show up in EEGlab.  
> \>   
> \> Configuration 2: Use the mexfile I compiled myself. The script freezes at the ppdev\_mex('Open', pportaddress);  
> \>   
> \> If I run the script as a normal user, I can get it to tell me "permission denied" for opening the parallel port:  
> \> /dev/parport0 Permission denied  
> \> error: ppdev\_mex: couldn't access port  
> \>   
> \>   
> \> If I give it the wrong address (2) I get   
> \>   
> \> /dev/parport1 No such file or directory  
> \> error: ppdev\_mex: couldn't access port  
> \>   
> \>   
> \> So it seems to be working basically right, but it is failing somewhere inside of opening the port.   
> \>   
> \> I'll probably switch to matlab now and see if I can get it to work that way, but I just wanted to give you feedback for this particular Octave/Ubuntu combination. Any advice would of course be welcome but thanks for this updated code in any case. I'll see if it works in matlab.  
> \>   
> \> with kind regards,  
> \>   
> \> Jonathan  
> \>   
> \>   
> \>   
> \>   
> \> On Sat, Oct 1, 2016 at 3:56 PM, Andreas Widmann [widmann@...](mailto:widmann@...)[PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> \> Mario was faster. Yes, ppdev-mex should compile under Octave (tested with Octave 4 on Ubuntu 16.04) and there is an Octave 64bit mex binary.  
> \>   
> \> Best,  
> \> Andreas  
> \>   
> \> \> Am 01.10.2016 um 19:36 schrieb [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\>:  
> \> \>   
> \> \>   
> \> \>   
> \> \> This one...  
> \> \>   
> \> \> [https://github.com/widmann/ppdev-mex](https://github.com/widmann/ppdev-mex)  
> \> \>   
> \> \> ... can only send TTL triggers over parallel port, but is reported to work very well under Octave. Had a query and success feedback for this just about a month ago.  
> \> \>   
> \> \> Hope it helps,  
> \> \> -mario   
> \> \>   
> \> \>   
> \>   
> \>   
> \>   
> \>   
> \>   
> \> --   
> \> Jonathan Folstein  
> \> Assistant Professor  
> \> Department of Psychology  
> \> Florida State University   
> \> 1107 W. Call St.   
> \> Tallahassee, FL 32306-4301  
> \> office: 850-645-0654  
> \> fax: 850-644-7739  
> \> [folstein@...](mailto:folstein@...)  
> \>   
> \>   
> \>

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 8, 2016, 2:21pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/6 "2016-10-08T14:21:34Z")

</div>

If you use the latest PTB beta from us (not yet in NeuroDebian), and run PsychLinuxConfiguration again, also the "user setup" section, and reboot the machine once, it should automatically add you to the 'lp' group for root-less access to the parallel port and make sure the interfering 'lp' parallel port line-printer driver is no longer loaded.  
  
Hopefully parallel port access with Andreas mex file should then work, but i couldn't test it with an actual parallel port - don't have one in my reach atm.  
  
If this automatic setup does/doesn't work, please let me know.  
-mario

---

<div class="post-metadata">

**Author:** ![folsteinlab](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@folsteinlab](https://psychtoolbox.discourse.group/u/folsteinlab)\
**Post date:** [October 9, 2016, 6:48pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/7 "2016-10-09T18:48:05Z")

</div>

Well, first thank you both so much for your quick and helpful replies. I started messing with things before Mario's reply. I had indeed neglected to add the user name to the group and comment out the lp line in the group file.   
  

The relevant line in /etc/group now reads:  
  

"lp:x:7:vpixx,root" (the root part was only added after a later PTB reinstallation)  
  
  

lsmod produces:  
  
vpixx@TestPC:~/Desktop/Experiments/AliensNM$ lsmod  
Module Size Used by  
snd\_hda\_codec\_hdmi 46368 1   
hp\_wmi 14062 0   
sparse\_keymap 13948 1 hp\_wmi  
rfcomm 69160 0   
bnep 19624 2   
bluetooth 395387 10 bnep,rfcomm  
snd\_hda\_codec\_realtek 65904 1   
x86\_pkg\_temp\_thermal 14205 0   
intel\_powerclamp 14705 0   
coretemp 13435 0   
snd\_hda\_intel 56562 5   
snd\_hda\_codec 193017 3 snd\_hda\_codec\_realtek,snd\_hda\_codec\_hdmi,snd\_hda\_intel  
kvm 459872 0   
snd\_hwdep 13602 1 snd\_hda\_codec  
snd\_pcm 102040 3 snd\_hda\_codec\_hdmi,snd\_hda\_codec,snd\_hda\_intel  
nvidia 10744943 39   
crct10dif\_pclmul 14250 0   
snd\_page\_alloc 18710 2 snd\_pcm,snd\_hda\_intel  
crc32\_pclmul 13113 0   
snd\_seq\_midi 13324 0   
snd\_seq\_midi\_event 14899 1 snd\_seq\_midi  
snd\_rawmidi 30682 1 snd\_seq\_midi  
aesni\_intel 55624 0   
aes\_x86\_64 17131 1 aesni\_intel  
snd\_seq 61567 2 snd\_seq\_midi\_event,snd\_seq\_midi  
joydev 17332 0   
lrw 13286 1 aesni\_intel  
gf128mul 14951 1 lrw  
glue\_helper 13990 1 aesni\_intel  
ablk\_helper 13597 1 aesni\_intel  
cryptd 20359 2 aesni\_intel,ablk\_helper  
snd\_seq\_device 14497 3 snd\_seq,snd\_rawmidi,snd\_seq\_midi  
snd\_timer 29500 2 snd\_pcm,snd\_seq  
serio\_raw 13413 0   
snd 69367 21 snd\_hda\_codec\_realtek,snd\_hwdep,snd\_timer,snd\_hda\_codec\_hdmi,snd\_pcm,snd\_seq,snd\_rawmidi,snd\_hda\_codec,snd\_hda\_intel,snd\_seq\_device,snd\_seq\_midi  
lpc\_ich 21080 0   
mei\_me 18627 0   
mei 82276 1 mei\_me  
soundcore 12680 1 snd  
drm 303102 2 nvidia  
parport\_pc 32701 1   
wmi 19177 1 hp\_wmi  
ppdev 17671 0   
tpm\_infineon 17372 0   
shpchp 37032 0   
mac\_hid 13205 0   
lp 17759 0   
parport 42299 3 lp,ppdev,parport\_pc  
hid\_generic 12548 0   
usbhid 48514 0   
hid 106148 2 hid\_generic,usbhid  
e1000e 254433 0   
ahci 34091 1   
psmouse 106643 0   
ptp 18933 1 e1000e  
libahci 32716 1 ahci  
pps\_core 19333 1 ptp  

  
  
  

The modules file now looks like:  
  
  
# This file contains the names of kernel modules that should be loaded  
# at boot time, one per line. Lines beginning with "#" are ignored.  
# Parameters can be specified after the module name.  
  
#lp  
rtc  
  

Unfortunately, the script still froze at the pport open command when I used the native compiled mex file. Oddly, if I opened octave as su, this happened:  

  

> 

\>\> testppmex  
 PPD ioctl 28811: -1 (No such device or address)  
pportaddress = 1  
setaddress  
error: ppdev\_mex: couldn't claim pport  
error: called from  
 testppmex at line 6 column 1  
  

Trying it with the octave mex file Andreas suggested, it crashed wanting a library associated with Octave 4. I then updated to Octave 4 and reinstalled PTB with DownloadPsychtoolbox. The setup did in fact add vpixx and root to the group. PTB seems to work fine. Unfortunately, the provided octave mex file and a newly compiled one caused the same behavior. Freezing at the Open command with no su and the error above calling octave as su.  
  

I know the parallel port card is working somehow because others have used it successfully from a Windows XP partition on the same computer.  
  

Thanks again for your help. Any further thoughts would be great.   

  

  

> On Sat, Oct 8, 2016 at 10:21 AM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> 
> > If you use the latest PTB beta from us (not yet in NeuroDebian), and run PsychLinuxConfiguration again, also the "user setup" section, and reboot the machine once, it should automatically add you to the 'lp' group for root-less access to the parallel port and make sure the interfering 'lp' parallel port line-printer driver is no longer loaded.  
> >   
> > Hopefully parallel port access with Andreas mex file should then work, but i couldn't test it with an actual parallel port - don't have one in my reach atm.  
> >   
> > If this automatic setup does/doesn't work, please let me know.  
> > -mario
> 
>   
>   
>   
> --   
> 
> Jonathan Folstein  
> Assistant Professor  
> Department of Psychology  
> Florida State University   
> 1107 W. Call St.   
> Tallahassee, FL 32306-4301
> office: 850-645-0654  
> 
> fax: 850-644-7739
> [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 9, 2016, 8:39pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/8 "2016-10-09T20:39:24Z")

</div>

Did you reboot after running the PTB setup again?  
  
If no, please do so.  
  
If yes, execute this ...  
sudo update-initramfs -u -k all  
... then reboot.  

  
Report which of those had an effect. "lsmod | grep lp" should not show a line with the "lp"module after such a reboot. "id" should show your vpixx user being a member of the "lp" group which allows non-root access to parallel ports.  
  
Currently the 'lp' module for driving good ol' parallel port line printers is still loaded, which will claim exclusive access to the port. PTB's setup should prevent that \_after\_ a reboot. But maybe i need to add a call to update-initramfs to the setup routine. Don't know if that is needed or not. Depends if parallel port setup is already done during early boot (while still running from within the initial ram disc aka initramfs), or only later after initial bootup. Without an actual parallel port i can't test that myself.  
  
-mario  
  
XX---In PSYCHTOOLBOX@yahoogroups.com, \<jonathan.r.folstein@...\> wrote :  
  

Well, first thank you both so much for your quick and helpful replies.&nbsp; I started messing with things before Mario's reply.&nbsp; I had indeed neglected to add the user name to the group and comment out the lp line in the group file.   
  

The relevant line in /etc/group now reads:  
  

"lp:x:7:vpixx,root" (the root part was only added after a later PTB reinstallation)  
  
  

lsmod produces:  
  
vpixx@TestPC:~/Desktop/Experiments/AliensNM$ lsmod  
Module&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Size&nbsp; Used by  
snd\_hda\_codec\_hdmi&nbsp;&nbsp;&nbsp;&nbsp; 46368&nbsp; 1   
hp\_wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14062&nbsp; 0   
sparse\_keymap&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13948&nbsp; 1 hp\_wmi  
rfcomm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69160&nbsp; 0   
bnep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19624&nbsp; 2   
bluetooth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 395387&nbsp; 10 bnep,rfcomm  
snd\_hda\_codec\_realtek&nbsp;&nbsp;&nbsp; 65904&nbsp; 1   
x86\_pkg\_temp\_thermal&nbsp;&nbsp;&nbsp; 14205&nbsp; 0   
intel\_powerclamp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14705&nbsp; 0   
coretemp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13435&nbsp; 0   
snd\_hda\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 56562&nbsp; 5   
snd\_hda\_codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 193017&nbsp; 3 snd\_hda\_codec\_realtek,snd\_hda\_codec\_hdmi,snd\_hda\_intel  
kvm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 459872&nbsp; 0   
snd\_hwdep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13602&nbsp; 1 snd\_hda\_codec  
snd\_pcm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 102040&nbsp; 3 snd\_hda\_codec\_hdmi,snd\_hda\_codec,snd\_hda\_intel  
nvidia&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 10744943&nbsp; 39   
crct10dif\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14250&nbsp; 0   
snd\_page\_alloc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18710&nbsp; 2 snd\_pcm,snd\_hda\_intel  
crc32\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13113&nbsp; 0   
snd\_seq\_midi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13324&nbsp; 0   
snd\_seq\_midi\_event&nbsp;&nbsp;&nbsp;&nbsp; 14899&nbsp; 1 snd\_seq\_midi  
snd\_rawmidi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 30682&nbsp; 1 snd\_seq\_midi  
aesni\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 55624&nbsp; 0   
aes\_x86\_64&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17131&nbsp; 1 aesni\_intel  
snd\_seq&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 61567&nbsp; 2 snd\_seq\_midi\_event,snd\_seq\_midi  
joydev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17332&nbsp; 0   
lrw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13286&nbsp; 1 aesni\_intel  
gf128mul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14951&nbsp; 1 lrw  
glue\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13990&nbsp; 1 aesni\_intel  
ablk\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13597&nbsp; 1 aesni\_intel  
cryptd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 20359&nbsp; 2 aesni\_intel,ablk\_helper  
snd\_seq\_device&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14497&nbsp; 3 snd\_seq,snd\_rawmidi,snd\_seq\_midi  
snd\_timer&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 29500&nbsp; 2 snd\_pcm,snd\_seq  
serio\_raw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13413&nbsp; 0   
snd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69367&nbsp; 21 snd\_hda\_codec\_realtek,snd\_hwdep,snd\_timer,snd\_hda\_codec\_hdmi,snd\_pcm,snd\_seq,snd\_rawmidi,snd\_hda\_codec,snd\_hda\_intel,snd\_seq\_device,snd\_seq\_midi  
lpc\_ich&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 21080&nbsp; 0   
mei\_me&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18627&nbsp; 0   
mei&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 82276&nbsp; 1 mei\_me  
soundcore&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12680&nbsp; 1 snd  
drm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 303102&nbsp; 2 nvidia  
parport\_pc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32701&nbsp; 1   
wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19177&nbsp; 1 hp\_wmi  
ppdev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17671&nbsp; 0   
tpm\_infineon&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17372&nbsp; 0   
shpchp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 37032&nbsp; 0   
mac\_hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13205&nbsp; 0   
lp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17759&nbsp; 0   
parport&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 42299&nbsp; 3 lp,ppdev,parport\_pc  
hid\_generic&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12548&nbsp; 0   
usbhid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 48514&nbsp; 0   
hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106148&nbsp; 2 hid\_generic,usbhid  
e1000e&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 254433&nbsp; 0   
ahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 34091&nbsp; 1   
psmouse&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106643&nbsp; 0   
ptp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18933&nbsp; 1 e1000e  
libahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32716&nbsp; 1 ahci  
pps\_core&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19333&nbsp; 1 ptp  

  
  
  

The modules file now looks like:  
  
  
# This file contains the names of kernel modules that should be loaded  
# at boot time, one per line. Lines beginning with "#" are ignored.  
# Parameters can be specified after the module name.  
  
#lp  
rtc  
  

Unfortunately, the script still froze at the pport open command when I used the native compiled mex file.&nbsp; Oddly, if I opened octave as su, this happened:  

  

> >

\>\> testppmex  
 PPD ioctl 28811: -1 (No such device or address)  
pportaddress =&nbsp; 1  
setaddress  
error: ppdev\_mex: couldn't claim pport  
error: called from  
&nbsp;&nbsp;&nbsp; testppmex at line 6 column 1  
  

Trying it with the octave mex file Andreas suggested, it crashed wanting a library associated with Octave 4.&nbsp; I then updated to Octave 4 and reinstalled PTB with DownloadPsychtoolbox.&nbsp; The setup did in fact add vpixx and root to the group. PTB seems to work fine. Unfortunately, the provided octave mex file and a newly compiled one caused the same behavior. Freezing at the Open command with no su and the error above calling octave as su.  
  

I know the parallel port card is working somehow because others have used it successfully from a Windows XP partition on the same computer.  
  

Thanks again for your help. Any further thoughts would be great.   

  

  

> On Sat, Oct 8, 2016 at 10:21 AM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> 
> > &nbsp;
> > 
> > If you use the latest PTB beta from us (not yet in NeuroDebian), and run PsychLinuxConfiguration again, also the "user setup" section, and reboot the machine once, it should automatically add you to the 'lp' group for root-less access to the parallel port and make sure the interfering 'lp' parallel port line-printer driver is no longer loaded.  
> >   
> > Hopefully parallel port access with Andreas mex file should then work, but i couldn't test it with an actual parallel port - don't have one in my reach atm.  
> >   
> > If this automatic setup does/doesn't work, please let me know.  
> > -mario
> 
>   
>   
>   
> --   
> 
> Jonathan Folstein  
> Assistant Professor  
> Department of Psychology  
> Florida State University   
> 1107 W. Call St.   
> Tallahassee, FL 32306-4301
> office: 850-645-0654  
> 
> fax: 850-644-7739
> [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![andreaswidmann](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@andreaswidmann](https://psychtoolbox.discourse.group/u/andreaswidmann)\
**Post date:** [October 10, 2016, 12:22pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/9 "2016-10-10T12:22:17Z")

</div>

> \> PPD ioctl 28811: -1 (No such device or address)

This is actually good news as it shows that the mex file itself compiled properly and works as expected but the lp module is still loaded. In addition to Mario’s suggestions another potential candidate is cups.  
  
In summary, please, check:  
\* /etc/modules: lp commented?  
\* /etc/modules-load.d/cups-filters.conf: lp commented?  
\* Does /etc/default/cups possibly exist? If yes, change "LOAD\_LP\_MODULE=yes" to "LOAD\_LP\_MODULE=no“ (actually should not exist as moved to cups-filters in 14.04 but who knows)  
\* /etc/modprobe.d/blacklist-psychtoolbox.conf: exists and lp NOT commented?  
\* sudo update-initramfs -u -k all  
\* reboot  
\* lsmod | grep lp  
\* lp module still loaded?  
  
Further, open issues are (a) the need for super-user privileges and (b) octave version compatibility. I would like to postpone sorting out (a).  
  
(b) I confirmed that the octave4 binary does not work under octave3 and vice versa. Mario, could you please give me a hint how to compile binaries running with both, octave 3 and 4 (as the PTB binaries do). Error message is missing liboctaveinterp.so.2 vs 3.  
  
Best,  
Andreas  
  
PS: I confirmed that the output of ppdev\_mex is consistent with documentation also with Octave (3 and 4).  
  

> \> Am 09.10.2016 um 22:39 schrieb [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\>:  
> \>   
> \>   
> \>   
> \> Did you reboot after running the PTB setup again?  
> \>   
> \> If no, please do so.  
> \>   
> \> If yes, execute this ...  
> \> sudo update-initramfs -u -k all  
> \> ... then reboot.  
> \>   
> \> Report which of those had an effect. "lsmod | grep lp" should not show a line with the "lp"module after such a reboot. "id" should show your vpixx user being a member of the "lp" group which allows non-root access to parallel ports.  
> \>   
> \> Currently the 'lp' module for driving good ol' parallel port line printers is still loaded, which will claim exclusive access to the port. PTB's setup should prevent that \_after\_ a reboot. But maybe i need to add a call to update-initramfs to the setup routine. Don't know if that is needed or not. Depends if parallel port setup is already done during early boot (while still running from within the initial ram disc aka initramfs), or only later after initial bootup. Without a n actual parallel port i can't test that myself.  
> \>   
> \> -mario  
> \>   
> \> XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<jonathan.r.folstein@...\> wrote :  
> \>   
> \> Well, first thank you both so much for your quick and helpful replies. I started messing with things before Mario's reply. I had indeed neglected to add the user name to the group and comment out the lp line in the group file.   
> \>   
> \> The relevant line in /etc/group now reads:  
> \>   
> \> "lp:x:7:vpixx,root" (the root part was only added after a later PTB reinstallation)  
> \>   
> \>   
> \> lsmod produces:  
> \>   
> \> vpixx@TestPC:~/Desktop/Experiments/AliensNM$ lsmod  
> \> Module Size Used by  
> \> snd\_hda\_codec\_hdmi 46368 1   
> \> hp\_wmi & nbsp; 14062 0   
> \> sparse\_keymap 13948 1 hp\_wmi  
> \> rfcomm 69160 0   
> \> bnep 19624 2   
> \> bluetooth 395387 10 bnep,rfcomm  
> \> snd\_hda\_codec\_realtek 65904 1   
> \> x86\_pkg\_temp\_thermal 14205 0   
> \> intel\_powerclamp 14705 0   
> \> coretemp 13435 0   
> \> snd\_hda\_intel 56562 5   
> \> snd\_hda\_codec 193017 3 snd\_hda\_codec\_realtek,snd\_hda\_codec\_hd mi,snd\_hda\_intel  
> \> kvm 459872 0   
> \> snd\_hwdep 13602 1 snd\_hda\_codec  
> \> snd\_pcm 102040 3 snd\_hda\_codec\_hdmi,snd\_hda\_codec,snd\_hda\_intel  
> \> nvidia 10744943 39   
> \> crct10dif\_pclmul 14250 0   
> \> snd\_page\_alloc 18710 2 snd\_pcm,snd\_hda\_intel  
> \> crc32\_pclmul 13113 0   
> \> snd\_seq\_midi 13324 0   
> \> snd\_seq\_midi\_event 14899 1 snd\_seq\_midi  
> \> snd\_rawmidi 30682 1 snd\_seq\_midi  
> \> aesni\_intel 55624 0   
> \> aes\_x86\_64 17131 1 aesni\_intel  
> \> snd\_seq 61567 2 snd\_seq\_midi\_event,snd\_seq\_midi  
> \> joydev 17332 0   
> \> lrw 13286 1 aesni\_intel  
> \> gf128mul 14951 1 lrw  
> \> glue\_helper 13990 1 aesni\_intel  
> \> ablk\_helper 13 597 1 aesni\_intel  
> \> cryptd 20359 2 aesni\_intel,ablk\_helper  
> \> snd\_seq\_device 14497 3 snd\_seq,snd\_rawmidi,snd\_seq\_midi  
> \> snd\_timer 29500 2 snd\_pcm,snd\_seq  
> \> serio\_raw 13413 0   
> \> snd 69367 21 snd\_hda\_codec\_realtek,snd\_hwdep,snd\_timer,snd\_hda\_codec\_hdmi,snd\_pcm,snd\_seq,snd\_rawmidi,snd\_hda\_codec,snd\_hda\_intel,snd\_seq\_device,snd\_seq\_midi  
> \> lpc\_ich 21080 0   
> \> mei\_me ; 18627 0   
> \> mei 82276 1 mei\_me  
> \> soundcore 12680 1 snd  
> \> drm 303102 2 nvidia  
> \> parport\_pc 32701 1   
> \> wmi 19177 1 hp\_wmi  
> \> ppdev 17671 0   
> \> tpm\_infineon 17372 0   
> \> shpchp 37032 0   
> \> mac\_hid 13205 0   
> \> lp 17759 0   
> \> parport 42299 3 lp,ppdev,parport\_pc  
> \> hid\_generic 12548 0   
> \> usbhid 48514 0   
> \> hid 106148 2 hid\_generic,usbhid  
> \> e1000e 254433 0   
> \> ahci 34091& nbsp; 1   
> \> psmouse 106643 0   
> \> ptp 18933 1 e1000e  
> \> libahci 32716 1 ahci  
> \> pps\_core 19333 1 ptp  
> \>   
> \>   
> \>   
> \> The modules file now looks like:  
> \>   
> \>   
> \> # This file contains the names of kernel modules that should be loaded  
> \> # at boot time, one per line. Lines beginning with "#" are ignored.  
> \> # Parameters can be specified after the module name.  
> \>   
> \> #lp  
> \> rtc  
> \>   
> \> Unfortunately, the script still froze at the pport open command when I used the native compiled mex file. Oddly, if I opened octave as su, this happened:  
> \> \>\> testppmex  
> \> PPD ioctl 28811: -1 (No such device or address)  
> \> pportaddress = 1  
> \> setaddress  
> \> error: ppdev\_mex: couldn't claim pport  
> \> error: called from  
> \> testppmex at line 6 column 1  
> \>   
> \> Trying it with the octave mex file Andreas suggested, it crashed wanting a library associated with Octave 4. I then updated to Octave 4 and reinstalled PTB with DownloadPsychtoolbox. The setup did in fact add vpixx and root to the group. PTB seems to work fine. Unfortunately, the provided octave mex file and a newly compiled one caused the same behavior. Freezing at the Open command with no su and the error above calling octave as su.  
> \>   
> \> I know the parallel port card is working somehow because others have used it successfully from a Windows XP partition on the same computer.  
> \>   
> \> Thanks again for your help. Any further thoughts would be great.   
> \>   
> \>   
> \> On Sat, Oct 8, 2016 at 10:21 AM, mario.kleiner@... [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> \>   
> \> If you use the latest PTB beta from us (not yet in NeuroDebian), and run PsychLinuxConfiguration again, also the "user setup" section, and reboot the machine once, it should automatically add you to the 'lp' group for root-less access to the parallel port and make sure the interfering 'lp' parallel port line-printer driver is no longer loaded.  
> \>   
> \> Hopefully parallel port access with Andreas mex file should then work, but i couldn't test it with an actual parallel port - don't have one in my reach atm.  
> \>   
> \> If this automatic setup does/doesn't work, please let me know.  
> \> -mario  
> \>   
> \>   
> \>   
> \>   
> \> --   
> \> Jonathan Folstein  
> \> Assistant Professor  
> \> Department of Psychology  
> \> Florida State University   
> \> 1107 W. Call St.   
> \> Tallahassee, FL 32306-4301  
> \> office: 850-645-0654  
> \> fax: 850-644-7739  
> \> folstein@...  
> \>   
> \>   
> \>

---

<div class="post-metadata">

**Author:** ![folsteinlab](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@folsteinlab](https://psychtoolbox.discourse.group/u/folsteinlab)\
**Post date:** [October 10, 2016, 3:02pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/10 "2016-10-10T15:02:15Z")

</div>

To foreshadow, this story has a happy ending. Read on.

Mere reboot: no effect

sudo update-initramfs -u -k all, then reboot: no effect

/etc/modules-load.d/cups-filters.conf DID exist and lp WAS uncommented. Changed it to:

# Parallel printer driver modules loading for cups

# LOAD\_LP\_MODULE was 'yes' in /etc/default/cups

#lp

ppdev

parport\_pc

/etc/default/cups: does exist but everything was commented, so I didn't change it:

# Cups configure options

# LOAD\_LP\_MODULE: enable/disable to load "lp" parallel printer driver module

# LOAD\_LP\_MODULE has migrated to /etc/modules-load.d/cups-filters.conf

# LOAD\_LP\_MODULE=yes

/etc/modprobe.d/blacklist-psychtoolbox.conf looks like (I didn't change it):

# Blacklist the lp modules for parallel port line printers.

# It would prevent exclusive use of ppdev for low-level

# parallel port access by Psychtoolbox.

blacklist lp

To evaluate the need for update-initramfs, I did the following:

1: UNCOMMENTED lp in cups-filters.conf

2: UNCOMMENTED lp in /etc/modules

3: REMOVED vpixx,root from lp group in /etc/group

4: ran sudo update-initramfs -u -k all

5: RECOMMENTED lp in cups-filters.conf

6: RECOMMENTED lp in /etc/modules

7: ADDED vpixx,root to lp group in /etc/group

8: rebooted

9: lsmod | grep did not produce an lp line:

vpixx@TestPC:~$ lsmod | grep lp

glue\_helper 13990 1 aesni\_intel  
ablk\_helper 13597 1 aesni\_intel  
cryptd 20359 2 aesni\_intel,ablk\_helper  
lpc\_ich 21080 0 

10: called testppmex from octave as normal user: STILL DID NOT WORK, freezes at ppdev\_mex('Open', pportaddress);

11: restarted octave as superuser: STILL DID NOT WORK, freezes at ppdev\_mex('Open', pportaddress);

12: ran sudo update-initramfs -u -k all

13: rebooted

14: called testppmex from octave as super user: STILL DID NOT WORK, freezes at ppdev\_mex('Open', pportaddress);

15: commented out the rest of /etc/modules-load.d/cups-filters.conf:

# Parallel printer driver modules loading for cups

# LOAD\_LP\_MODULE was 'yes' in /etc/default/cups   
  
#lp   
#ppdev   
#parport\_pc 

16: rebooted

17: called testppmex from octave as super user: STILL DID NOT WORK, freezes at ppdev\_mex('Open', pportaddress);

18: ran sudo update-initramfs -u -k all

19: rebooted

20: called testppmex from octave as super user, omg the joy IT WORKS:

> \>\> testppmex

pportaddress = 1

setaddress

opened port

bitarray =

0

0

1

0

0

1

1

0

sent a stim ttl

bitarray =

0

0

1

0

0

1

1

0

sent a stim ttl

bitarray =

0

0

1

0

0

1

1

0

sent a stim ttl

...note that output of bitarray is correct: I told it to 'Write' 100 in the script

21: called testppmex from octave as normal user (from the octave gui), STILL WORKS

22: connected amplifiers and started BrainVision Recorder (EEG recording app receiving event codes), called testtrigger.m

23: IT WORKS. The codes are detected by Recorder.

In conclusion:

comment out all lines in /etc/modules-load.d/cups-filters.conf

comment out lp in /etc/modules

add yourself to the lp group in /etc/group if PTB hasn't done it already

at this time the update-initramfs step appears necessary

when “bitarray = ppdev\_mex('Write', pportaddress, 100)” is called, bitarray produces the correct output.

Superuser does not appear necessary when everything is working right.

Boom drop the mic (note to self, learn linux).

But seriously, thanks for the help.

Cheers,

Jonathan

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 11, 2016, 9:49pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/11 "2016-10-11T21:49:05Z")

</div>

Thanks for the info! Hopefully this won't be needed in the future anymore:  
  
I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
  
The file now looks like this, with the new redirection of lp to /bin/false:  
  
# Blacklist the lp modules for parallel port line printers.  
# It would prevent exclusive use of ppdev for low-level  
# parallel port access by Psychtoolbox.  
blacklist lp  
install lp /bin/false  
  
Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
  
sudo usermod -a -G lp myusername  
  
command to add user myusername to group 'lp'.  
  
best,  
-mario

---

<div class="post-metadata">

**Author:** ![folsteinlab](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@folsteinlab](https://psychtoolbox.discourse.group/u/folsteinlab)\
**Post date:** [October 11, 2016, 9:59pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/12 "2016-10-11T21:59:06Z")

</div>

Um, I'm actually really depressed right now because Ubuntu installed some updates and now ppdev\_mex stopped working. It freezes during the Open command.  
  

All of the settings above are completely unchanged and I added install lp /bin/false to the blacklist file as you suggested.  
  

lsmod produces:  
  
Module Size Used by  
snd\_hda\_codec\_hdmi 46368 1   
rfcomm 69160 0   
bnep 19624 2   
bluetooth 395387 10 bnep,rfcomm  
snd\_hda\_codec\_realtek 65904 1   
mei\_me 18627 0   
mei 82276 1 mei\_me  
snd\_hda\_intel 56562 5   
ppdev 17671 6   
snd\_hda\_codec 193017 3 snd\_hda\_codec\_realtek,snd\_hda\_codec\_hdmi,snd\_hda\_intel  
hp\_wmi 14062 0   
nvidia 10561198 39   
x86\_pkg\_temp\_thermal 14205 0   
intel\_powerclamp 14705 0   
sparse\_keymap 13948 1 hp\_wmi  
snd\_hwdep 13602 1 snd\_hda\_codec  
coretemp 13435 0   
snd\_pcm 102040 3 snd\_hda\_codec\_hdmi,snd\_hda\_codec,snd\_hda\_intel  
kvm 459872 0   
snd\_page\_alloc 18710 2 snd\_pcm,snd\_hda\_intel  
snd\_seq\_midi 13324 0   
joydev 17332 0   
snd\_seq\_midi\_event 14899 1 snd\_seq\_midi  
crct10dif\_pclmul 14250 0   
crc32\_pclmul 13113 0   
aesni\_intel 55624 0   
aes\_x86\_64 17131 1 aesni\_intel  
lrw 13286 1 aesni\_intel  
snd\_rawmidi 30682 1 snd\_seq\_midi  
gf128mul 14951 1 lrw  
glue\_helper 13990 1 aesni\_intel  
ablk\_helper 13597 1 aesni\_intel  
cryptd 20359 2 aesni\_intel,ablk\_helper  
drm 303102 2 nvidia  
serio\_raw 13413 0   
snd\_seq 61567 2 snd\_seq\_midi\_event,snd\_seq\_midi  
snd\_seq\_device 14497 3 snd\_seq,snd\_rawmidi,snd\_seq\_midi  
snd\_timer 29500 2 snd\_pcm,snd\_seq  
parport\_pc 32701 2   
snd 69367 21 snd\_hda\_codec\_realtek,snd\_hwdep,snd\_timer,snd\_hda\_codec\_hdmi,snd\_pcm,snd\_seq,snd\_rawmidi,snd\_hda\_codec,snd\_hda\_intel,snd\_seq\_device,snd\_seq\_midi  
parport 42299 2 ppdev,parport\_pc  
shpchp 37032 0   
soundcore 12680 1 snd  
lpc\_ich 21080 0   
wmi 19177 1 hp\_wmi  
tpm\_infineon 17372 0   
mac\_hid 13205 0   
hid\_generic 12548 0   
usbhid 48514 0   
hid 106148 2 hid\_generic,usbhid  
e1000e 254433 0   
ahci 34091 1   
psmouse 106643 0   
ptp 18933 1 e1000e  
libahci 32716 1 ahci  
pps\_core 19333 1 ptp  
  
  

see anything suspicious?  

  

  

> On Tue, Oct 11, 2016 at 5:49 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> 
> > Thanks for the info! Hopefully this won't be needed in the future anymore:  
> >   
> > I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
> >   
> > The file now looks like this, with the new redirection of lp to /bin/false:  
> >   
> > # Blacklist the lp modules for parallel port line printers.  
> > # It would prevent exclusive use of ppdev for low-level  
> > # parallel port access by Psychtoolbox.  
> > blacklist lp  
> > install lp /bin/false  
> >   
> > Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
> >   
> > sudo usermod -a -G lp myusername  
> >   
> > command to add user myusername to group 'lp'.  
> >   
> > best,  
> > -mario
> 
>   
>   
>   
> --   
> 
> Jonathan Folstein  
> Assistant Professor  
> Department of Psychology  
> Florida State University   
> 1107 W. Call St.   
> Tallahassee, FL 32306-4301
> office: 850-645-0654  
> 
> fax: 850-644-7739
> [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 12, 2016, 12:28pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/13 "2016-10-12T12:28:42Z")

</div>

XX---In PSYCHTOOLBOX@yahoogroups.com, \<jonathan.r.folstein@...\> wrote :  

  

Um, I'm actually really depressed right now because Ubuntu installed some updates and now ppdev\_mex stopped working. It freezes during the Open command.  
  
-\> Most surprising. Cheap alcohol helps a lot to cope with computer problems.  
  

All of the settings above are completely unchanged and I added install lp /bin/false to the blacklist file as you suggested.  
  
-\> Ran PsychLinuxConfiguration + Reboot again? I wonder if your manual editing of the groups file could have caused some problems?  
  
-\> That said, i don't see anything suspicious in the output below. The 'lp' module doesn't seem to be loaded, so it can't block the parport, i can't see anything else blocking it either. I looked at the driver source code and afaics the reason for blocking (in the PPCLAIM ioctl()) is if some other higher level driver would claim access to the port, but afaik 'lp' is the only one doing this on a typical standard setup.  
  
This is a regular builtin PC parallel port, right? Is there anything related to the parallel port in the output of the 'dmesg' command after the failure?  
  
"strace octave --no-gui" might also help to see in which function call it actually blocks. I can't test anything here further without access to an actual computer with parallel port, but this used to work just fine when i still had such machines, so this is surprising.  
  
-mario  
  

lsmod produces:  
  
Module&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Size&nbsp; Used by  
snd\_hda\_codec\_hdmi&nbsp;&nbsp;&nbsp;&nbsp; 46368&nbsp; 1   
rfcomm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69160&nbsp; 0   
bnep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19624&nbsp; 2   
bluetooth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 395387&nbsp; 10 bnep,rfcomm  
snd\_hda\_codec\_realtek&nbsp;&nbsp;&nbsp; 65904&nbsp; 1   
mei\_me&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18627&nbsp; 0   
mei&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 82276&nbsp; 1 mei\_me  
snd\_hda\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 56562&nbsp; 5   
ppdev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17671&nbsp; 6   
snd\_hda\_codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 193017&nbsp; 3 snd\_hda\_codec\_realtek,snd\_hda\_codec\_hdmi,snd\_hda\_intel  
hp\_wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14062&nbsp; 0   
nvidia&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 10561198&nbsp; 39   
x86\_pkg\_temp\_thermal&nbsp;&nbsp;&nbsp; 14205&nbsp; 0   
intel\_powerclamp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14705&nbsp; 0   
sparse\_keymap&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13948&nbsp; 1 hp\_wmi  
snd\_hwdep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13602&nbsp; 1 snd\_hda\_codec  
coretemp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13435&nbsp; 0   
snd\_pcm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 102040&nbsp; 3 snd\_hda\_codec\_hdmi,snd\_hda\_codec,snd\_hda\_intel  
kvm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 459872&nbsp; 0   
snd\_page\_alloc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18710&nbsp; 2 snd\_pcm,snd\_hda\_intel  
snd\_seq\_midi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13324&nbsp; 0   
joydev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17332&nbsp; 0   
snd\_seq\_midi\_event&nbsp;&nbsp;&nbsp;&nbsp; 14899&nbsp; 1 snd\_seq\_midi  
crct10dif\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14250&nbsp; 0   
crc32\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13113&nbsp; 0   
aesni\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 55624&nbsp; 0   
aes\_x86\_64&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17131&nbsp; 1 aesni\_intel  
lrw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13286&nbsp; 1 aesni\_intel  
snd\_rawmidi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 30682&nbsp; 1 snd\_seq\_midi  
gf128mul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14951&nbsp; 1 lrw  
glue\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13990&nbsp; 1 aesni\_intel  
ablk\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13597&nbsp; 1 aesni\_intel  
cryptd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 20359&nbsp; 2 aesni\_intel,ablk\_helper  
drm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 303102&nbsp; 2 nvidia  
serio\_raw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13413&nbsp; 0   
snd\_seq&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 61567&nbsp; 2 snd\_seq\_midi\_event,snd\_seq\_midi  
snd\_seq\_device&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14497&nbsp; 3 snd\_seq,snd\_rawmidi,snd\_seq\_midi  
snd\_timer&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 29500&nbsp; 2 snd\_pcm,snd\_seq  
parport\_pc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32701&nbsp; 2   
snd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69367&nbsp; 21 snd\_hda\_codec\_realtek,snd\_hwdep,snd\_timer,snd\_hda\_codec\_hdmi,snd\_pcm,snd\_seq,snd\_rawmidi,snd\_hda\_codec,snd\_hda\_intel,snd\_seq\_device,snd\_seq\_midi  
parport&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 42299&nbsp; 2 ppdev,parport\_pc  
shpchp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 37032&nbsp; 0   
soundcore&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12680&nbsp; 1 snd  
lpc\_ich&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 21080&nbsp; 0   
wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19177&nbsp; 1 hp\_wmi  
tpm\_infineon&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17372&nbsp; 0   
mac\_hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13205&nbsp; 0   
hid\_generic&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12548&nbsp; 0   
usbhid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 48514&nbsp; 0   
hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106148&nbsp; 2 hid\_generic,usbhid  
e1000e&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 254433&nbsp; 0   
ahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 34091&nbsp; 1   
psmouse&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106643&nbsp; 0   
ptp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18933&nbsp; 1 e1000e  
libahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32716&nbsp; 1 ahci  
pps\_core&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19333&nbsp; 1 ptp  
  
  

see anything suspicious?  

  

  

> > On Tue, Oct 11, 2016 at 5:49 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > 
> > > &nbsp;
> > > 
> > > Thanks for the info! Hopefully this won't be needed in the future anymore:  
> > >   
> > > I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
> > >   
> > > The file now looks like this, with the new redirection of lp to /bin/false:  
> > >   
> > > # Blacklist the lp modules for parallel port line printers.  
> > > # It would prevent exclusive use of ppdev for low-level  
> > > # parallel port access by Psychtoolbox.  
> > > blacklist lp  
> > > install lp /bin/false  
> > >   
> > > Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
> > >   
> > > sudo usermod -a -G lp myusername  
> > >   
> > > command to add user myusername to group 'lp'.  
> > >   
> > > best,  
> > > -mario
> > 
> >   
> >   
> >   
> > --   
> > 
> > Jonathan Folstein  
> > Assistant Professor  
> > Department of Psychology  
> > Florida State University   
> > 1107 W. Call St.   
> > Tallahassee, FL 32306-4301
> > office: 850-645-0654  
> > 
> > fax: 850-644-7739
> > [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 12, 2016, 12:48pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/14 "2016-10-12T12:48:10Z")

</div>

Hm, the output of "lsof /dev/parport0" could also give some hint if some other running application got a hold of the parport.  

  
-mario  
  

XX---In PSYCHTOOLBOX@yahoogroups.com, \<jonathan.r.folstein@...\> wrote :  

  

Um, I'm actually really depressed right now because Ubuntu installed some updates and now ppdev\_mex stopped working. It freezes during the Open command.  
  
-\> Most surprising. Cheap alcohol helps a lot to cope with computer problems.  
  

All of the settings above are completely unchanged and I added install lp /bin/false to the blacklist file as you suggested.  
  
-\> Ran PsychLinuxConfiguration + Reboot again? I wonder if your manual editing of the groups file could have caused some problems?  
  
-\> That said, i don't see anything suspicious in the output below. The 'lp' module doesn't seem to be loaded, so it can't block the parport, i can't see anything else blocking it either. I looked at the driver source code and afaics the reason for blocking (in the PPCLAIM ioctl()) is if some other higher level driver would claim access to the port, but afaik 'lp' is the only one doing this on a typical standard setup.  
  
This is a regular builtin PC parallel port, right? Is there anything related to the parallel port in the output of the 'dmesg' command after the failure?  
  
"strace octave --no-gui" might also help to see in which function call it actually blocks. I can't test anything here further without access to an actual computer with parallel port, but this used to work just fine when i still had such machines, so this is surprising.  
  
-mario  
  

lsmod produces:  
  
Module&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Size&nbsp; Used by  
snd\_hda\_codec\_hdmi&nbsp;&nbsp;&nbsp;&nbsp; 46368&nbsp; 1   
rfcomm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69160&nbsp; 0   
bnep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19624&nbsp; 2   
bluetooth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 395387&nbsp; 10 bnep,rfcomm  
snd\_hda\_codec\_realtek&nbsp;&nbsp;&nbsp; 65904&nbsp; 1   
mei\_me&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18627&nbsp; 0   
mei&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 82276&nbsp; 1 mei\_me  
snd\_hda\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 56562&nbsp; 5   
ppdev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17671&nbsp; 6   
snd\_hda\_codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 193017&nbsp; 3 snd\_hda\_codec\_realtek,snd\_hda\_codec\_hdmi,snd\_hda\_intel  
hp\_wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14062&nbsp; 0   
nvidia&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 10561198&nbsp; 39   
x86\_pkg\_temp\_thermal&nbsp;&nbsp;&nbsp; 14205&nbsp; 0   
intel\_powerclamp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14705&nbsp; 0   
sparse\_keymap&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13948&nbsp; 1 hp\_wmi  
snd\_hwdep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13602&nbsp; 1 snd\_hda\_codec  
coretemp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13435&nbsp; 0   
snd\_pcm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 102040&nbsp; 3 snd\_hda\_codec\_hdmi,snd\_hda\_codec,snd\_hda\_intel  
kvm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 459872&nbsp; 0   
snd\_page\_alloc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18710&nbsp; 2 snd\_pcm,snd\_hda\_intel  
snd\_seq\_midi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13324&nbsp; 0   
joydev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17332&nbsp; 0   
snd\_seq\_midi\_event&nbsp;&nbsp;&nbsp;&nbsp; 14899&nbsp; 1 snd\_seq\_midi  
crct10dif\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14250&nbsp; 0   
crc32\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13113&nbsp; 0   
aesni\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 55624&nbsp; 0   
aes\_x86\_64&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17131&nbsp; 1 aesni\_intel  
lrw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13286&nbsp; 1 aesni\_intel  
snd\_rawmidi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 30682&nbsp; 1 snd\_seq\_midi  
gf128mul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14951&nbsp; 1 lrw  
glue\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13990&nbsp; 1 aesni\_intel  
ablk\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13597&nbsp; 1 aesni\_intel  
cryptd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 20359&nbsp; 2 aesni\_intel,ablk\_helper  
drm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 303102&nbsp; 2 nvidia  
serio\_raw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13413&nbsp; 0   
snd\_seq&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 61567&nbsp; 2 snd\_seq\_midi\_event,snd\_seq\_midi  
snd\_seq\_device&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14497&nbsp; 3 snd\_seq,snd\_rawmidi,snd\_seq\_midi  
snd\_timer&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 29500&nbsp; 2 snd\_pcm,snd\_seq  
parport\_pc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32701&nbsp; 2   
snd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69367&nbsp; 21 snd\_hda\_codec\_realtek,snd\_hwdep,snd\_timer,snd\_hda\_codec\_hdmi,snd\_pcm,snd\_seq,snd\_rawmidi,snd\_hda\_codec,snd\_hda\_intel,snd\_seq\_device,snd\_seq\_midi  
parport&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 42299&nbsp; 2 ppdev,parport\_pc  
shpchp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 37032&nbsp; 0   
soundcore&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12680&nbsp; 1 snd  
lpc\_ich&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 21080&nbsp; 0   
wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19177&nbsp; 1 hp\_wmi  
tpm\_infineon&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17372&nbsp; 0   
mac\_hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13205&nbsp; 0   
hid\_generic&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12548&nbsp; 0   
usbhid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 48514&nbsp; 0   
hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106148&nbsp; 2 hid\_generic,usbhid  
e1000e&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 254433&nbsp; 0   
ahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 34091&nbsp; 1   
psmouse&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106643&nbsp; 0   
ptp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18933&nbsp; 1 e1000e  
libahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32716&nbsp; 1 ahci  
pps\_core&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19333&nbsp; 1 ptp  
  
  

see anything suspicious?  

  

  

> > > On Tue, Oct 11, 2016 at 5:49 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > 
> > > > &nbsp;
> > > > 
> > > > Thanks for the info! Hopefully this won't be needed in the future anymore:  
> > > >   
> > > > I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
> > > >   
> > > > The file now looks like this, with the new redirection of lp to /bin/false:  
> > > >   
> > > > # Blacklist the lp modules for parallel port line printers.  
> > > > # It would prevent exclusive use of ppdev for low-level  
> > > > # parallel port access by Psychtoolbox.  
> > > > blacklist lp  
> > > > install lp /bin/false  
> > > >   
> > > > Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
> > > >   
> > > > sudo usermod -a -G lp myusername  
> > > >   
> > > > command to add user myusername to group 'lp'.  
> > > >   
> > > > best,  
> > > > -mario
> > > 
> > >   
> > >   
> > >   
> > > --   
> > > 
> > > Jonathan Folstein  
> > > Assistant Professor  
> > > Department of Psychology  
> > > Florida State University   
> > > 1107 W. Call St.   
> > > Tallahassee, FL 32306-4301
> > > office: 850-645-0654  
> > > 
> > > fax: 850-644-7739
> > > [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![folsteinlab](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@folsteinlab](https://psychtoolbox.discourse.group/u/folsteinlab)\
**Post date:** [October 12, 2016, 1:41pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/15 "2016-10-12T13:41:22Z")

</div>

> On Wed, Oct 12, 2016 at 8:48 AM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> 
> > Hm, the output of "lsof /dev/parport0" could also give some hint if some other running application got a hold of the parport.
> 
> This gives a blank.  
>   
> 
> Here's some output from dmesg after the failure. To be clear, it freezes and I have to press ^C  
>   
> [240.220918] INFO: task python:459 blocked for more than 120 seconds.  
> [240.220929] Tainted: P OX 3.13.0-96-lowlatency #143-Ubuntu  
> [240.220932] "echo 0 \> /proc/sys/kernel/hung\_task\_timeout\_secs" disables this message.  
> [240.220936] python D ffff88022dd93300 0 459 1 0x00000000  
> [240.220945] ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> [240.220954] ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> [240.220960] ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> [240.220968] Call Trace:  
> [240.220992] [\<ffffffff81732761\>] schedule\_preempt\_disabled+0x31/0x80  
> [240.221000] [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/0x200  
> [240.221009] [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> [240.221018] [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> [240.221027] [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> [240.221037] [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> [240.221044] [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> [240.221051] [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
> [265.656105] octave-gui (2372): Using mlock ulimits for SHM\_HUGETLB is deprecated  
> [360.117575] INFO: task python:459 blocked for more than 120 seconds.  
> [360.117586] Tainted: P OX 3.13.0-96-lowlatency #143-Ubuntu  
> [360.117589] "echo 0 \> /proc/sys/kernel/hung\_task\_timeout\_secs" disables this message.  
> [360.117593] python D ffff88022dd93300 0 459 1 0x00000000  
> [360.117602] ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> [360.117611] ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> [360.117617] ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> [360.117625] Call Trace:  
> [360.117650] [\<ffffffff81732761\>] schedule\_preempt\_disabled+0x31/0x80  
> [360.117659] [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/0x200  
> [360.117668] [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> [360.117676] [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> [360.117685] [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> [360.117696] [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> [360.117702] [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> [360.117709] [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
>   
> 
>   
>  
> 
> > -mario
> > 
> >   
> >   
> > 
> > XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<jonathan.r.folstein@...\> wrote :  
> > 
> >   
> > 
> > Um, I'm actually really depressed right now because Ubuntu installed some updates and now ppdev\_mex stopped working. It freezes during the Open command.  
> >   
> > -\> Most surprising. Cheap alcohol helps a lot to cope with computer problems.  
> >   
> > 
> > All of the settings above are completely unchanged and I added install lp /bin/false to the blacklist file as you suggested.  
> >   
> > -\> Ran PsychLinuxConfiguration + Reboot again? I wonder if your manual editing of the groups file could have caused some problems?  
> >   
> > -\> That said, i don't see anything suspicious in the output below. The 'lp' module doesn't seem to be loaded, so it can't block the parport, i can't see anything else blocking it either. I looked at the driver source code and afaics the reason for blocking (in the PPCLAIM ioctl()) is if some other higher level driver would claim access to the port, but afaik 'lp' is the only one doing this on a typical standard setup.  
> >   
> > This is a regular builtin PC parallel port, right? Is there anything related to the parallel port in the output of the 'dmesg' command after the failure?  
> >   
> > "strace octave --no-gui" might also help to see in which function call it actually blocks. I can't test anything here further without access to an actual computer with parallel port, but this used to work just fine when i still had such machines, so this is surprising.  
> >   
> > -mario  
> >   
> > 
> > lsmod produces:  
> >   
> > Module Size Used by  
> > snd\_hda\_codec\_hdmi 46368 1   
> > rfcomm 69160 0   
> > bnep 19624 2   
> > bluetooth 395387 10 bnep,rfcomm  
> > snd\_hda\_codec\_realtek 65904 1   
> > mei\_me 18627 0   
> > mei 82276 1 mei\_me  
> > snd\_hda\_intel 56562 5   
> > ppdev 17671 6   
> > snd\_hda\_codec 193017 3 snd\_hda\_codec\_realtek,snd\_hda\_ codec\_hdmi,snd\_hda\_intel  
> > hp\_wmi 14062 0   
> > nvidia 10561198 39   
> > x86\_pkg\_temp\_thermal 14205 0   
> > intel\_powerclamp 14705 0   
> > sparse\_keymap 13948 1 hp\_wmi  
> > snd\_hwdep 13602 1 snd\_hda\_codec  
> > coretemp 13435 0   
> > snd\_pcm 102040 3 snd\_hda\_codec\_hdmi,snd\_hda\_ codec,snd\_hda\_intel  
> > kvm 459872 0   
> > snd\_page\_alloc 18710 2 snd\_pcm,snd\_hda\_intel  
> > snd\_seq\_midi 13324 0   
> > joydev 17332 0   
> > snd\_seq\_midi\_event 14899 1 snd\_seq\_midi  
> > crct10dif\_pclmul 14250 0   
> > crc32\_pclmul 13113 0   
> > aesni\_intel 55624 0   
> > aes\_x86\_64 17131 1 aesni\_intel  
> > lrw 13286 1 aesni\_intel  
> > snd\_rawmidi 30682 1 snd\_seq\_midi  
> > gf128mul 14951 1 lrw  
> > glue\_helper 13990 1 aesni\_intel  
> > ablk\_helper 13597 1 aesni\_intel  
> > cryptd 20359 2 aesni\_intel,ablk\_helper  
> > drm 303102 2 nvidia  
> > serio\_raw 13413 0   
> > snd\_seq 61567 2 snd\_seq\_midi\_event,snd\_seq\_ midi  
> > snd\_seq\_device 14497 3 snd\_seq,snd\_rawmidi,snd\_seq\_ midi  
> > snd\_timer 29500 2 snd\_pcm,snd\_seq  
> > parport\_pc 32701 2   
> > snd 69367 21 snd\_hda\_codec\_realtek,snd\_ hwdep,snd\_timer,snd\_hda\_codec\_ hdmi,snd\_pcm,snd\_seq,snd\_ rawmidi,snd\_hda\_codec,snd\_hda\_ intel,snd\_seq\_device,snd\_seq\_ midi  
> > parport 42299 2 ppdev,parport\_pc  
> > shpchp 37032 0   
> > soundcore 12680 1 snd  
> > lpc\_ich 21080 0   
> > wmi 19177 1 hp\_wmi  
> > tpm\_infineon 17372 0   
> > mac\_hid 13205 0   
> > hid\_generic 12548 0   
> > usbhid 48514 0   
> > hid 106148 2 hid\_generic,usbhid  
> > e1000e 254433 0   
> > ahci 34091 1   
> > psmouse 106643 0   
> > ptp 18933 1 e1000e  
> > libahci 32716 1 ahci  
> > pps\_core 19333 1 ptp  
> >   
> >   
> > 
> > see anything suspicious?  
> > 
> >   
> > 
> >   
> > 
> > > > On Tue, Oct 11, 2016 at 5:49 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > > 
> > > > > Thanks for the info! Hopefully this won't be needed in the future anymore:  
> > > > >   
> > > > > I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
> > > > >   
> > > > > The file now looks like this, with the new redirection of lp to /bin/false:  
> > > > >   
> > > > > # Blacklist the lp modules for parallel port line printers.  
> > > > > # It would prevent exclusive use of ppdev for low-level  
> > > > > # parallel port access by Psychtoolbox.  
> > > > > blacklist lp  
> > > > > install lp /bin/false  
> > > > >   
> > > > > Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
> > > > >   
> > > > > sudo usermod -a -G lp myusername  
> > > > >   
> > > > > command to add user myusername to group 'lp'.  
> > > > >   
> > > > > best,  
> > > > > -mario
> > > > 
> > > >   
> > > >   
> > > >   
> > > > --   
> > > > 
> > > > Jonathan Folstein  
> > > > Assistant Professor  
> > > > Department of Psychology  
> > > > Florida State University   
> > > > 1107 W. Call St.   
> > > > Tallahassee, FL 32306-4301
> > > > office: 850-645-0654  
> > > > 
> > > > fax: 850-644-7739
> > > > [folstein@...](mailto:folstein@...)
> 
>   
>   
>   
> --   
> 
> Jonathan Folstein  
> Assistant Professor  
> Department of Psychology  
> Florida State University   
> 1107 W. Call St.   
> Tallahassee, FL 32306-4301
> office: 850-645-0654  
> 
> fax: 850-644-7739
> [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 12, 2016, 7:16pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/16 "2016-10-12T19:16:39Z")

</div>

Doesn't make much sense to me, because in your debug output, the ppdev and parport\_pc module were already loaded. ppdev is needed because that's what the mex file uses, and parport\_pc is needed to drive the actual parallel port hardware. Maybe something else "fixed" it during the reboot, as a side effect of your change. But let's see how it goes.  

  
All i know is from the driver source code that there was a potential bug related to this that could cause a deadlock if the timing - or the order in which driver modules got loaded - was just right (or just wrong) and that got fixed mid 2015. So that bug is present in your 3.13 kernel but not in more modern kernels post mid 2015.  
  
The kernel i recommended is the kernel used in Ubuntu 14.04.5-LTS and in Ubuntu 16.04-LTS. Essentially the hw support of 14.04.5-LTS is identical to the one in 16.04-LTS.  
  
-mario  
  
XX---In PSYCHTOOLBOX@yahoogroups.com, \<jonathan.r.folstein@...\> wrote :  
  

Ok, I fixed it by again editing /etc/modules-load.d/cups-filters.conf  
  

Prior to the updates, the script wouldn't work until the file looked like this:  

  
# Parallel printer driver modules loading for cups  
# LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
#lp  
#ppdev  
#parport\_pc  
  
  
  

..or this (didn't matter):   
  
# Parallel printer driver modules loading for cups  
# LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
#lp  
ppdev  
#parport\_pc  
  

  
  

Now it won't work until it looks like this:  
  
# Parallel printer driver modules loading for cups  
# LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
#lp  
ppdev  
parport\_pc  
  
  

...and then of course calling initramfs and rebooting.  
  

argh, there you have it.  

  

  

> > On Wed, Oct 12, 2016 at 9:41 AM, Jonathan Folstein \<[jonathan.r.folstein@...](mailto:jonathan.r.folstein@...)\> wrote:  
> > 
> > > On Wed, Oct 12, 2016 at 8:48 AM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > 
> > > > &nbsp;
> > > > 
> > > > Hm, the output of "lsof /dev/parport0" could also give some hint if some other running application got a hold of the parport.
> > > 
> > > This gives a blank.  
> > >   
> > > 
> > > Here's some output from dmesg after the failure.&nbsp; To be clear, it freezes and I have to press ^C  
> > >   
> > > [&nbsp; 240.220918] INFO: task python:459 blocked for more than 120 seconds.  
> > > [&nbsp; 240.220929]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Tainted: P&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; OX 3.13.0-96-lowlatency #143-Ubuntu  
> > > [&nbsp; 240.220932] "echo 0 \> /proc/sys/kernel/hung\_task\_ timeout\_secs" disables this message.  
> > > [&nbsp; 240.220936] python&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; D ffff88022dd93300&nbsp;&nbsp;&nbsp;&nbsp; 0&nbsp;&nbsp; 459&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1 0x00000000  
> > > [&nbsp; 240.220945]&nbsp; ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> > > [&nbsp; 240.220954]&nbsp; ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> > > [&nbsp; 240.220960]&nbsp; ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> > > [&nbsp; 240.220968] Call Trace:  
> > > [&nbsp; 240.220992]&nbsp; [\<ffffffff81732761\>] schedule\_preempt\_disabled+ 0x31/0x80  
> > > [&nbsp; 240.221000]&nbsp; [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/ 0x200  
> > > [&nbsp; 240.221009]&nbsp; [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> > > [&nbsp; 240.221018]&nbsp; [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> > > [&nbsp; 240.221027]&nbsp; [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> > > [&nbsp; 240.221037]&nbsp; [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> > > [&nbsp; 240.221044]&nbsp; [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> > > [&nbsp; 240.221051]&nbsp; [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
> > > [&nbsp; 265.656105] octave-gui (2372): Using mlock ulimits for SHM\_HUGETLB is deprecated  
> > > [&nbsp; 360.117575] INFO: task python:459 blocked for more than 120 seconds.  
> > > [&nbsp; 360.117586]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Tainted: P&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; OX 3.13.0-96-lowlatency #143-Ubuntu  
> > > [&nbsp; 360.117589] "echo 0 \> /proc/sys/kernel/hung\_task\_ timeout\_secs" disables this message.  
> > > [&nbsp; 360.117593] python&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; D ffff88022dd93300&nbsp;&nbsp;&nbsp;&nbsp; 0&nbsp;&nbsp; 459&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1 0x00000000  
> > > [&nbsp; 360.117602]&nbsp; ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> > > [&nbsp; 360.117611]&nbsp; ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> > > [&nbsp; 360.117617]&nbsp; ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> > > [&nbsp; 360.117625] Call Trace:  
> > > [&nbsp; 360.117650]&nbsp; [\<ffffffff81732761\>] schedule\_preempt\_disabled+ 0x31/0x80  
> > > [&nbsp; 360.117659]&nbsp; [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/ 0x200  
> > > [&nbsp; 360.117668]&nbsp; [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> > > [&nbsp; 360.117676]&nbsp; [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> > > [&nbsp; 360.117685]&nbsp; [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> > > [&nbsp; 360.117696]&nbsp; [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> > > [&nbsp; 360.117702]&nbsp; [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> > > [&nbsp; 360.117709]&nbsp; [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
> > >   
> > > 
> > >   
> > > &nbsp;
> > > 
> > > > -mario
> > > > 
> > > >   
> > > >   
> > > > 
> > > > XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<jonathan.r.folstein@...\> wrote :  
> > > > 
> > > >   
> > > > 
> > > > Um, I'm actually really depressed right now because Ubuntu installed some updates and now ppdev\_mex stopped working. It freezes during the Open command.  
> > > >   
> > > > -\> Most surprising. Cheap alcohol helps a lot to cope with computer problems.  
> > > >   
> > > > 
> > > > All of the settings above are completely unchanged and I added install lp /bin/false to the blacklist file as you suggested.  
> > > >   
> > > > -\> Ran PsychLinuxConfiguration + Reboot again? I wonder if your manual editing of the groups file could have caused some problems?  
> > > >   
> > > > -\> That said, i don't see anything suspicious in the output below. The 'lp' module doesn't seem to be loaded, so it can't block the parport, i can't see anything else blocking it either. I looked at the driver source code and afaics the reason for blocking (in the PPCLAIM ioctl()) is if some other higher level driver would claim access to the port, but afaik 'lp' is the only one doing this on a typical standard setup.  
> > > >   
> > > > This is a regular builtin PC parallel port, right? Is there anything related to the parallel port in the output of the 'dmesg' command after the failure?  
> > > >   
> > > > "strace octave --no-gui" might also help to see in which function call it actually blocks. I can't test anything here further without access to an actual computer with parallel port, but this used to work just fine when i still had such machines, so this is surprising.  
> > > >   
> > > > -mario  
> > > >   
> > > > 
> > > > lsmod produces:  
> > > >   
> > > > Module&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Size&nbsp; Used by  
> > > > snd\_hda\_codec\_hdmi&nbsp;&nbsp;&nbsp;&nbsp; 46368&nbsp; 1   
> > > > rfcomm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69160&nbsp; 0   
> > > > bnep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19624&nbsp; 2   
> > > > bluetooth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 395387&nbsp; 10 bnep,rfcomm  
> > > > snd\_hda\_codec\_realtek&nbsp;&nbsp;&nbsp; 65904&nbsp; 1   
> > > > mei\_me&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18627&nbsp; 0   
> > > > mei&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 82276&nbsp; 1 mei\_me  
> > > > snd\_hda\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 56562&nbsp; 5   
> > > > ppdev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17671&nbsp; 6   
> > > > snd\_hda\_codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 193017&nbsp; 3 snd\_hda\_codec\_realtek,snd\_hda\_ codec\_hdmi,snd\_hda\_intel  
> > > > hp\_wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14062&nbsp; 0   
> > > > nvidia&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 10561198&nbsp; 39   
> > > > x86\_pkg\_temp\_thermal&nbsp;&nbsp;&nbsp; 14205&nbsp; 0   
> > > > intel\_powerclamp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14705&nbsp; 0   
> > > > sparse\_keymap&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13948&nbsp; 1 hp\_wmi  
> > > > snd\_hwdep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13602&nbsp; 1 snd\_hda\_codec  
> > > > coretemp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13435&nbsp; 0   
> > > > snd\_pcm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 102040&nbsp; 3 snd\_hda\_codec\_hdmi,snd\_hda\_cod ec,snd\_hda\_intel  
> > > > kvm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 459872&nbsp; 0   
> > > > snd\_page\_alloc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18710&nbsp; 2 snd\_pcm,snd\_hda\_intel  
> > > > snd\_seq\_midi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13324&nbsp; 0   
> > > > joydev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17332&nbsp; 0   
> > > > snd\_seq\_midi\_event&nbsp;&nbsp;&nbsp;&nbsp; 14899&nbsp; 1 snd\_seq\_midi  
> > > > crct10dif\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14250&nbsp; 0   
> > > > crc32\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13113&nbsp; 0   
> > > > aesni\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 55624&nbsp; 0   
> > > > aes\_x86\_64&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17131&nbsp; 1 aesni\_intel  
> > > > lrw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13286&nbsp; 1 aesni\_intel  
> > > > snd\_rawmidi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 30682&nbsp; 1 snd\_seq\_midi  
> > > > gf128mul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14951&nbsp; 1 lrw  
> > > > glue\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13990&nbsp; 1 aesni\_intel  
> > > > ablk\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13597&nbsp; 1 aesni\_intel  
> > > > cryptd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 20359&nbsp; 2 aesni\_intel,ablk\_helper  
> > > > drm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 303102&nbsp; 2 nvidia  
> > > > serio\_raw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13413&nbsp; 0   
> > > > snd\_seq&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 61567&nbsp; 2 snd\_seq\_midi\_event,snd\_seq\_mid i  
> > > > snd\_seq\_device&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14497&nbsp; 3 snd\_seq,snd\_rawmidi,snd\_seq\_mi di  
> > > > snd\_timer&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 29500&nbsp; 2 snd\_pcm,snd\_seq  
> > > > parport\_pc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32701&nbsp; 2   
> > > > snd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69367&nbsp; 21 snd\_hda\_codec\_realtek,snd\_hwde p,snd\_timer,snd\_hda\_codec\_hdmi ,snd\_pcm,snd\_seq,snd\_rawmidi, snd\_hda\_codec,snd\_hda\_intel, snd\_seq\_device,snd\_seq\_midi  
> > > > parport&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 42299&nbsp; 2 ppdev,parport\_pc  
> > > > shpchp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 37032&nbsp; 0   
> > > > soundcore&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12680&nbsp; 1 snd  
> > > > lpc\_ich&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 21080&nbsp; 0   
> > > > wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19177&nbsp; 1 hp\_wmi  
> > > > tpm\_infineon&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17372&nbsp; 0   
> > > > mac\_hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13205&nbsp; 0   
> > > > hid\_generic&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12548&nbsp; 0   
> > > > usbhid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 48514&nbsp; 0   
> > > > hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106148&nbsp; 2 hid\_generic,usbhid  
> > > > e1000e&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 254433&nbsp; 0   
> > > > ahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 34091&nbsp; 1   
> > > > psmouse&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106643&nbsp; 0   
> > > > ptp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18933&nbsp; 1 e1000e  
> > > > libahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32716&nbsp; 1 ahci  
> > > > pps\_core&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19333&nbsp; 1 ptp  
> > > >   
> > > >   
> > > > 
> > > > see anything suspicious?  
> > > > 
> > > >   
> > > > 
> > > >   
> > > > 
> > > > > > On Tue, Oct 11, 2016 at 5:49 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > > > > 
> > > > > > > &nbsp;
> > > > > > > 
> > > > > > > Thanks for the info! Hopefully this won't be needed in the future anymore:  
> > > > > > >   
> > > > > > > I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
> > > > > > >   
> > > > > > > The file now looks like this, with the new redirection of lp to /bin/false:  
> > > > > > >   
> > > > > > > # Blacklist the lp modules for parallel port line printers.  
> > > > > > > # It would prevent exclusive use of ppdev for low-level  
> > > > > > > # parallel port access by Psychtoolbox.  
> > > > > > > blacklist lp  
> > > > > > > install lp /bin/false  
> > > > > > >   
> > > > > > > Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
> > > > > > >   
> > > > > > > sudo usermod -a -G lp myusername  
> > > > > > >   
> > > > > > > command to add user myusername to group 'lp'.  
> > > > > > >   
> > > > > > > best,  
> > > > > > > -mario
> > > > > > 
> > > > > >   
> > > > > >   
> > > > > >   
> > > > > > --   
> > > > > > 
> > > > > > Jonathan Folstein  
> > > > > > Assistant Professor  
> > > > > > Department of Psychology  
> > > > > > Florida State University   
> > > > > > 1107 W. Call St.   
> > > > > > Tallahassee, FL 32306-4301
> > > > > > office: 850-645-0654  
> > > > > > 
> > > > > > fax: 850-644-7739
> > > > > > [folstein@...](mailto:folstein@...)
> > > 
> > >   
> > >   
> > >   
> > > --   
> > > 
> > > Jonathan Folstein  
> > > Assistant Professor  
> > > Department of Psychology  
> > > Florida State University   
> > > 1107 W. Call St.   
> > > Tallahassee, FL 32306-4301
> > > office: 850-645-0654  
> > > 
> > > fax: 850-644-7739
> > > 
> > > [folstein@...](mailto:folstein@...)
> > 
> >   
> >   
> >   
> > --   
> > 
> > Jonathan Folstein  
> > Assistant Professor  
> > Department of Psychology  
> > Florida State University   
> > 1107 W. Call St.   
> > Tallahassee, FL 32306-4301
> > office: 850-645-0654  
> > 
> > fax: 850-644-7739
> > [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![folsteinlab](https://avatars.discourse-cdn.com/v4/letter/f/71c47a/32.png) [@folsteinlab](https://psychtoolbox.discourse.group/u/folsteinlab)\
**Post date:** [October 14, 2016, 4:54pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/17 "2016-10-14T16:54:11Z")

</div>

Ok, updated the kernel as you suggested and ppdev\_mex stopped working again. Who knows if the update had anything to do with it or if something random changed in the background. Anyway, I updated to 16.04 and happily it seems to work. I'll keep you posted.  

  

> On Wed, Oct 12, 2016 at 3:16 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> 
> > Doesn't make much sense to me, because in your debug output, the ppdev and parport\_pc module were already loaded. ppdev is needed because that's what the mex file uses, and parport\_pc is needed to drive the actual parallel port hardware. Maybe something else "fixed" it during the reboot, as a side effect of your change. But let's see how it goes.
> > 
> >   
> > All i know is from the driver source code that there was a potential bug related to this that could cause a deadlock if the timing - or the order in which driver modules got loaded - was just right (or just wrong) and that got fixed mid 2015. So that bug is present in your 3.13 kernel but not in more modern kernels post mid 2015.  
> >   
> > The kernel i recommended is the kernel used in Ubuntu 14.04.5-LTS and in Ubuntu 16.04-LTS. Essentially the hw support of 14.04.5-LTS is identical to the one in 16.04-LTS.  
> >   
> > -mario  
> >   
> > XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<jonathan.r.folstein@...\> wrote :  
> >   
> > 
> > Ok, I fixed it by again editing /etc/modules-load.d/cups- filters.conf  
> >   
> > 
> > Prior to the updates, the script wouldn't work until the file looked like this:  
> > 
> >   
> > # Parallel printer driver modules loading for cups  
> > # LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
> > #lp  
> > #ppdev  
> > #parport\_pc  
> >   
> >   
> >   
> > 
> > ..or this (didn't matter):   
> >   
> > # Parallel printer driver modules loading for cups  
> > # LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
> > #lp  
> > ppdev  
> > #parport\_pc  
> >   
> > 
> >   
> >   
> > 
> > Now it won't work until it looks like this:  
> >   
> > # Parallel printer driver modules loading for cups  
> > # LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
> > #lp  
> > ppdev  
> > parport\_pc  
> >   
> >   
> > 
> > ...and then of course calling initramfs and rebooting.  
> >   
> > 
> > argh, there you have it.  
> > 
> >   
> > 
> >   
> > 
> > > On Wed, Oct 12, 2016 at 9:41 AM, Jonathan Folstein \<[jonathan.r.folstein@...](mailto:jonathan.r.folstein@...)\> wrote:  
> > > 
> > > > On Wed, Oct 12, 2016 at 8:48 AM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > > 
> > > > > Hm, the output of "lsof /dev/parport0" could also give some hint if some other running application got a hold of the parport.
> > > > 
> > > > This gives a blank.  
> > > >   
> > > > 
> > > > Here's some output from dmesg after the failure. To be clear, it freezes and I have to press ^C  
> > > >   
> > > > [240.220918] INFO: task python:459 blocked for more than 120 seconds.  
> > > > [240.220929] Tainted: P OX 3.13.0-96-lowlatency #143-Ubuntu  
> > > > [240.220932] "echo 0 \> /proc/sys/kernel/hung\_task\_ timeout\_secs" disables this message.  
> > > > [240.220936] python D ffff88022dd93300 0 459 1 0x00000000  
> > > > [240.220945] ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> > > > [240.220954] ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> > > > [240.220960] ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> > > > [240.220968] Call Trace:  
> > > > [240.220992] [\<ffffffff81732761\>] schedule\_preempt\_disabled+ 0x31/0x80  
> > > > [240.221000] [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/ 0x200  
> > > > [240.221009] [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> > > > [240.221018] [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> > > > [240.221027] [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> > > > [240.221037] [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> > > > [240.221044] [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> > > > [240.221051] [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
> > > > [265.656105] octave-gui (2372): Using mlock ulimits for SHM\_HUGETLB is deprecated  
> > > > [360.117575] INFO: task python:459 blocked for more than 120 seconds.  
> > > > [360.117586] Tainted: P OX 3.13.0-96-lowlatency #143-Ubuntu  
> > > > [360.117589] "echo 0 \> /proc/sys/kernel/hung\_task\_ timeout\_secs" disables this message.
> > > > 
> > > >   
> > > > [360.117593] python D ffff88022dd93300 0 459 1 0x00000000  
> > > > [360.117602] ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> > > > [360.117611] ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> > > > [360.117617] ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> > > > [360.117625] Call Trace:  
> > > > [360.117650] [\<ffffffff81732761\>] schedule\_preempt\_disabled+ 0x31/0x80  
> > > > [360.117659] [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/ 0x200  
> > > > [360.117668] [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> > > > [360.117676] [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> > > > [360.117685] [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> > > > [360.117696] [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> > > > [360.117702] [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> > > > [360.117709] [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
> > > >   
> > > > 
> > > >   
> > > >  
> > > > 
> > > > > -mario
> > > > > 
> > > > >   
> > > > >   
> > > > > 
> > > > > XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<jonathan.r.folstein@...\> wrote :  
> > > > > 
> > > > >   
> > > > > 
> > > > > Um, I'm actually really depressed right now because Ubuntu installed some updates and now ppdev\_mex stopped working. It freezes during the Open command.  
> > > > >   
> > > > > -\> Most surprising. Cheap alcohol helps a lot to cope with computer problems.  
> > > > >   
> > > > > 
> > > > > All of the settings above are completely unchanged and I added install lp /bin/false to the blacklist file as you suggested.  
> > > > >   
> > > > > -\> Ran PsychLinuxConfiguration + Reboot again? I wonder if your manual editing of the groups file could have caused some problems?  
> > > > >   
> > > > > -\> That said, i don't see anything suspicious in the output below. The 'lp' module doesn't seem to be loaded, so it can't block the parport, i can't see anything else blocking it either. I looked at the driver source code and afaics the reason for blocking (in the PPCLAIM ioctl()) is if some other higher level driver would claim access to the port, but afaik 'lp' is the only one doing this on a typical standard setup.  
> > > > >   
> > > > > This is a regular builtin PC parallel port, right? Is there anything related to the parallel port in the output of the 'dmesg' command after the failure?  
> > > > >   
> > > > > "strace octave --no-gui" might also help to see in which function call it actually blocks. I can't test anything here further without access to an actual computer with parallel port, but this used to work just fine when i still had such machines, so this is surprising.  
> > > > >   
> > > > > -mario  
> > > > >   
> > > > > 
> > > > > lsmod produces:  
> > > > >   
> > > > > Module Size Used by  
> > > > > snd\_hda\_codec\_hdmi 46368 1   
> > > > > rfcomm 69160 0   
> > > > > bnep 19624 2   
> > > > > bluetooth 395387 10 bnep,rfcomm  
> > > > > snd\_hda\_codec\_realtek 65904 1   
> > > > > mei\_me 18627 0   
> > > > > mei 82276 1 mei\_me  
> > > > > snd\_hda\_intel 56562 5   
> > > > > ppdev 17671 6   
> > > > > snd\_hda\_codec 193017 3 snd\_hda\_codec\_realtek,snd\_hda\_ codec\_hdmi,snd\_hda\_intel  
> > > > > hp\_wmi 14062 0   
> > > > > nvidia 10561198 39   
> > > > > x86\_pkg\_temp\_thermal 14205 0   
> > > > > intel\_powerclamp 14705 0   
> > > > > sparse\_keymap 13948 1 hp\_wmi  
> > > > > snd\_hwdep 13602 1 snd\_hda\_codec  
> > > > > coretemp 13435 0   
> > > > > snd\_pcm 102040 3 snd\_hda\_codec\_hdmi,snd\_hda\_cod ec,snd\_hda\_intel  
> > > > > kvm 459872 0   
> > > > > snd\_page\_alloc 18710 2 snd\_pcm,snd\_hda\_intel  
> > > > > snd\_seq\_midi 13324 0   
> > > > > joydev 17332 0   
> > > > > snd\_seq\_midi\_event 14899 1 snd\_seq\_midi  
> > > > > crct10dif\_pclmul 14250 0   
> > > > > crc32\_pclmul 13113 0   
> > > > > aesni\_intel 55624 0   
> > > > > aes\_x86\_64 17131 1 aesni\_intel  
> > > > > lrw 13286 1 aesni\_intel  
> > > > > snd\_rawmidi 30682 1 snd\_seq\_midi  
> > > > > gf128mul 14951 1 lrw  
> > > > > glue\_helper 13990 1 aesni\_intel  
> > > > > ablk\_helper 13597 1 aesni\_intel  
> > > > > cryptd 20359 2 aesni\_intel,ablk\_helper  
> > > > > drm 303102 2 nvidia  
> > > > > serio\_raw 13413 0   
> > > > > 
> > > > > snd\_seq 61567 2 snd\_seq\_midi\_event,snd\_seq\_mid i  
> > > > > snd\_seq\_device 14497 3 snd\_seq,snd\_rawmidi,snd\_seq\_mi di  
> > > > > 
> > > > > snd\_timer 29500 2 snd\_pcm,snd\_seq  
> > > > > parport\_pc 32701 2   
> > > > > snd 69367 21 snd\_hda\_codec\_realtek,snd\_hwde p,snd\_timer,snd\_hda\_codec\_hdmi ,snd\_pcm,snd\_seq,snd\_rawmidi, snd\_hda\_codec,snd\_hda\_intel, snd\_seq\_device,snd\_seq\_midi  
> > > > > parport 42299 2 ppdev,parport\_pc  
> > > > > shpchp 37032 0   
> > > > > soundcore 12680 1 snd  
> > > > > lpc\_ich 21080 0   
> > > > > wmi 19177 1 hp\_wmi  
> > > > > tpm\_infineon 17372 0   
> > > > > mac\_hid 13205 0   
> > > > > hid\_generic 12548 0   
> > > > > usbhid 48514 0   
> > > > > hid 106148 2 hid\_generic,usbhid  
> > > > > e1000e 254433 0   
> > > > > ahci 34091 1   
> > > > > psmouse 106643 0   
> > > > > ptp 18933 1 e1000e  
> > > > > libahci 32716 1 ahci  
> > > > > pps\_core 19333 1 ptp  
> > > > >   
> > > > >   
> > > > > 
> > > > > see anything suspicious?  
> > > > > 
> > > > >   
> > > > > 
> > > > >   
> > > > > 
> > > > > > > On Tue, Oct 11, 2016 at 5:49 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > > > > > 
> > > > > > > > Thanks for the info! Hopefully this won't be needed in the future anymore:  
> > > > > > > >   
> > > > > > > > I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
> > > > > > > >   
> > > > > > > > The file now looks like this, with the new redirection of lp to /bin/false:  
> > > > > > > >   
> > > > > > > > # Blacklist the lp modules for parallel port line printers.  
> > > > > > > > # It would prevent exclusive use of ppdev for low-level  
> > > > > > > > # parallel port access by Psychtoolbox.  
> > > > > > > > blacklist lp  
> > > > > > > > install lp /bin/false  
> > > > > > > >   
> > > > > > > > Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
> > > > > > > >   
> > > > > > > > sudo usermod -a -G lp myusername  
> > > > > > > >   
> > > > > > > > command to add user myusername to group 'lp'.  
> > > > > > > >   
> > > > > > > > best,  
> > > > > > > > -mario
> > > > > > > 
> > > > > > >   
> > > > > > >   
> > > > > > >   
> > > > > > > --   
> > > > > > > 
> > > > > > > Jonathan Folstein  
> > > > > > > Assistant Professor  
> > > > > > > Department of Psychology  
> > > > > > > Florida State University   
> > > > > > > 1107 W. Call St.   
> > > > > > > Tallahassee, FL 32306-4301
> > > > > > > office: 850-645-0654  
> > > > > > > 
> > > > > > > fax: 850-644-7739
> > > > > > > [folstein@...](mailto:folstein@...)
> > > > 
> > > >   
> > > >   
> > > >   
> > > > --   
> > > > 
> > > > Jonathan Folstein  
> > > > Assistant Professor  
> > > > Department of Psychology  
> > > > Florida State University   
> > > > 1107 W. Call St.   
> > > > Tallahassee, FL 32306-4301
> > > > office: 850-645-0654  
> > > > 
> > > > fax: 850-644-7739
> > > > 
> > > > [folstein@...](mailto:folstein@...)
> > > 
> > >   
> > >   
> > >   
> > > --   
> > > 
> > > Jonathan Folstein  
> > > Assistant Professor  
> > > Department of Psychology  
> > > Florida State University   
> > > 1107 W. Call St.   
> > > Tallahassee, FL 32306-4301
> > > office: 850-645-0654  
> > > 
> > > fax: 850-644-7739
> > > [folstein@...](mailto:folstein@...)
> 
>   
>   
>   
> --   
> 
> Jonathan Folstein  
> Assistant Professor  
> Department of Psychology  
> Florida State University   
> 1107 W. Call St.   
> Tallahassee, FL 32306-4301
> office: 850-645-0654  
> 
> fax: 850-644-7739
> [folstein@...](mailto:folstein@...)

---

<div class="post-metadata">

**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [October 14, 2016, 5:52pm UTC](https://psychtoolbox.discourse.group/t/ttl-triggers-method-2/577/18 "2016-10-14T17:52:55Z")

</div>

Good. Andreas Widmann who wrote ppdev\_mex is also on 16.04.1 and doesn't seem to have these kind of problems, so maybe it helps.  

  
In general i spent a huge ton of time testing - and also improving some bits of the kernel and graphics stack of - 16.04 LTS before its release on the set of hardware we have here (though not parallel ports as i don't have any), and from that i can not think of any downsides to upgrading from 14.04 to 16.04, only various improvements.  
  
Currently i'm testing PTB on both 14.04 and 16.04, but i intend to switch my laptop to 16.04 soon, and then i will only test and tweak for 16.04 LTS. Ubuntu 14.04.5 LTS has the same kernel and graphics stack as 16.04 though, so if one has to stick to 14.04, upgrading to 14.04.5 is the right thing to do.  
  
-mario  
  
In PSYCHTOOLBOX@yahoogroups.com, \<jonathan.r.folstein@...\> wrote :  
  

Ok, updated the kernel as you suggested and ppdev\_mex stopped working again.&nbsp; Who knows if the update had anything to do with it or if something random changed in the background.&nbsp; Anyway, I updated to 16.04 and happily it seems to work. I'll keep you posted.  

  

> > On Wed, Oct 12, 2016 at 3:16 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > 
> > > &nbsp;
> > > 
> > > Doesn't make much sense to me, because in your debug output, the ppdev and parport\_pc module were already loaded. ppdev is needed because that's what the mex file uses, and parport\_pc is needed to drive the actual parallel port hardware. Maybe something else "fixed" it during the reboot, as a side effect of your change. But let's see how it goes.
> > > 
> > >   
> > > All i know is from the driver source code that there was a potential bug related to this that could cause a deadlock if the timing - or the order in which driver modules got loaded - was just right (or just wrong) and that got fixed mid 2015. So that bug is present in your 3.13 kernel but not in more modern kernels post mid 2015.  
> > >   
> > > The kernel i recommended is the kernel used in Ubuntu 14.04.5-LTS and in Ubuntu 16.04-LTS. Essentially the hw support of 14.04.5-LTS is identical to the one in 16.04-LTS.  
> > >   
> > > -mario  
> > >   
> > > XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<jonathan.r.folstein@...\> wrote :  
> > >   
> > > 
> > > Ok, I fixed it by again editing /etc/modules-load.d/cups- filters.conf  
> > >   
> > > 
> > > Prior to the updates, the script wouldn't work until the file looked like this:  
> > > 
> > >   
> > > # Parallel printer driver modules loading for cups  
> > > # LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
> > > #lp  
> > > #ppdev  
> > > #parport\_pc  
> > >   
> > >   
> > >   
> > > 
> > > ..or this (didn't matter):   
> > >   
> > > # Parallel printer driver modules loading for cups  
> > > # LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
> > > #lp  
> > > ppdev  
> > > #parport\_pc  
> > >   
> > > 
> > >   
> > >   
> > > 
> > > Now it won't work until it looks like this:  
> > >   
> > > # Parallel printer driver modules loading for cups  
> > > # LOAD\_LP\_MODULE was 'yes' in /etc/default/cups  
> > > #lp  
> > > ppdev  
> > > parport\_pc  
> > >   
> > >   
> > > 
> > > ...and then of course calling initramfs and rebooting.  
> > >   
> > > 
> > > argh, there you have it.  
> > > 
> > >   
> > > 
> > >   
> > > 
> > > > On Wed, Oct 12, 2016 at 9:41 AM, Jonathan Folstein \<[jonathan.r.folstein@...](mailto:jonathan.r.folstein@...)\> wrote:  
> > > > 
> > > > > On Wed, Oct 12, 2016 at 8:48 AM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > > > 
> > > > > > &nbsp;
> > > > > > 
> > > > > > Hm, the output of "lsof /dev/parport0" could also give some hint if some other running application got a hold of the parport.
> > > > > 
> > > > > This gives a blank.  
> > > > >   
> > > > > 
> > > > > Here's some output from dmesg after the failure.&nbsp; To be clear, it freezes and I have to press ^C  
> > > > >   
> > > > > [&nbsp; 240.220918] INFO: task python:459 blocked for more than 120 seconds.  
> > > > > [&nbsp; 240.220929]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Tainted: P&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; OX 3.13.0-96-lowlatency #143-Ubuntu  
> > > > > [&nbsp; 240.220932] "echo 0 \> /proc/sys/kernel/hung\_task\_ timeout\_secs" disables this message.  
> > > > > [&nbsp; 240.220936] python&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; D ffff88022dd93300&nbsp;&nbsp;&nbsp;&nbsp; 0&nbsp;&nbsp; 459&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1 0x00000000  
> > > > > [&nbsp; 240.220945]&nbsp; ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> > > > > [&nbsp; 240.220954]&nbsp; ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> > > > > [&nbsp; 240.220960]&nbsp; ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> > > > > [&nbsp; 240.220968] Call Trace:  
> > > > > [&nbsp; 240.220992]&nbsp; [\<ffffffff81732761\>] schedule\_preempt\_disabled+ 0x31/0x80  
> > > > > [&nbsp; 240.221000]&nbsp; [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/ 0x200  
> > > > > [&nbsp; 240.221009]&nbsp; [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> > > > > [&nbsp; 240.221018]&nbsp; [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> > > > > [&nbsp; 240.221027]&nbsp; [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> > > > > [&nbsp; 240.221037]&nbsp; [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> > > > > [&nbsp; 240.221044]&nbsp; [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> > > > > [&nbsp; 240.221051]&nbsp; [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
> > > > > [&nbsp; 265.656105] octave-gui (2372): Using mlock ulimits for SHM\_HUGETLB is deprecated  
> > > > > [&nbsp; 360.117575] INFO: task python:459 blocked for more than 120 seconds.  
> > > > > [&nbsp; 360.117586]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Tainted: P&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; OX 3.13.0-96-lowlatency #143-Ubuntu  
> > > > > [&nbsp; 360.117589] "echo 0 \> /proc/sys/kernel/hung\_task\_ timeout\_secs" disables this message.
> > > > > 
> > > > >   
> > > > > [&nbsp; 360.117593] python&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; D ffff88022dd93300&nbsp;&nbsp;&nbsp;&nbsp; 0&nbsp;&nbsp; 459&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1 0x00000000  
> > > > > [&nbsp; 360.117602]&nbsp; ffff8800bda33e10 0000000000000086 ffff880221688000 0000000000013300  
> > > > > [&nbsp; 360.117611]&nbsp; ffff8800bda33fd8 0000000000013300 ffff880221688000 ffffffffa028d040  
> > > > > [&nbsp; 360.117617]&nbsp; ffffffffa028d044 ffff880221688000 00000000ffffffff ffffffffa028d048  
> > > > > [&nbsp; 360.117625] Call Trace:  
> > > > > [&nbsp; 360.117650]&nbsp; [\<ffffffff81732761\>] schedule\_preempt\_disabled+ 0x31/0x80  
> > > > > [&nbsp; 360.117659]&nbsp; [\<ffffffff81734395\>] \_\_mutex\_lock\_slowpath+0x165/ 0x200  
> > > > > [&nbsp; 360.117668]&nbsp; [\<ffffffff81734447\>] mutex\_lock+0x17/0x27  
> > > > > [&nbsp; 360.117676]&nbsp; [\<ffffffffa028acc3\>] pp\_ioctl+0x23/0x50 [ppdev]  
> > > > > [&nbsp; 360.117685]&nbsp; [\<ffffffff811d7a40\>] do\_vfs\_ioctl+0x2e0/0x4c0  
> > > > > [&nbsp; 360.117696]&nbsp; [\<ffffffff811d46c2\>] ? final\_putname+0x22/0x50  
> > > > > [&nbsp; 360.117702]&nbsp; [\<ffffffff811d7ca1\>] SyS\_ioctl+0x81/0xa0  
> > > > > [&nbsp; 360.117709]&nbsp; [\<ffffffff8173da1d\>] system\_call\_fastpath+0x1a/0x1f  
> > > > >   
> > > > > 
> > > > >   
> > > > > &nbsp;
> > > > > 
> > > > > > -mario
> > > > > > 
> > > > > >   
> > > > > >   
> > > > > > 
> > > > > > XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<jonathan.r.folstein@...\> wrote :  
> > > > > > 
> > > > > >   
> > > > > > 
> > > > > > Um, I'm actually really depressed right now because Ubuntu installed some updates and now ppdev\_mex stopped working. It freezes during the Open command.  
> > > > > >   
> > > > > > -\> Most surprising. Cheap alcohol helps a lot to cope with computer problems.  
> > > > > >   
> > > > > > 
> > > > > > All of the settings above are completely unchanged and I added install lp /bin/false to the blacklist file as you suggested.  
> > > > > >   
> > > > > > -\> Ran PsychLinuxConfiguration + Reboot again? I wonder if your manual editing of the groups file could have caused some problems?  
> > > > > >   
> > > > > > -\> That said, i don't see anything suspicious in the output below. The 'lp' module doesn't seem to be loaded, so it can't block the parport, i can't see anything else blocking it either. I looked at the driver source code and afaics the reason for blocking (in the PPCLAIM ioctl()) is if some other higher level driver would claim access to the port, but afaik 'lp' is the only one doing this on a typical standard setup.  
> > > > > >   
> > > > > > This is a regular builtin PC parallel port, right? Is there anything related to the parallel port in the output of the 'dmesg' command after the failure?  
> > > > > >   
> > > > > > "strace octave --no-gui" might also help to see in which function call it actually blocks. I can't test anything here further without access to an actual computer with parallel port, but this used to work just fine when i still had such machines, so this is surprising.  
> > > > > >   
> > > > > > -mario  
> > > > > >   
> > > > > > 
> > > > > > lsmod produces:  
> > > > > >   
> > > > > > Module&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Size&nbsp; Used by  
> > > > > > snd\_hda\_codec\_hdmi&nbsp;&nbsp;&nbsp;&nbsp; 46368&nbsp; 1   
> > > > > > rfcomm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69160&nbsp; 0   
> > > > > > bnep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19624&nbsp; 2   
> > > > > > bluetooth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 395387&nbsp; 10 bnep,rfcomm  
> > > > > > snd\_hda\_codec\_realtek&nbsp;&nbsp;&nbsp; 65904&nbsp; 1   
> > > > > > mei\_me&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18627&nbsp; 0   
> > > > > > mei&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 82276&nbsp; 1 mei\_me  
> > > > > > snd\_hda\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 56562&nbsp; 5   
> > > > > > ppdev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17671&nbsp; 6   
> > > > > > snd\_hda\_codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 193017&nbsp; 3 snd\_hda\_codec\_realtek,snd\_hda\_ codec\_hdmi,snd\_hda\_intel  
> > > > > > hp\_wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14062&nbsp; 0   
> > > > > > nvidia&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 10561198&nbsp; 39   
> > > > > > x86\_pkg\_temp\_thermal&nbsp;&nbsp;&nbsp; 14205&nbsp; 0   
> > > > > > intel\_powerclamp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14705&nbsp; 0   
> > > > > > sparse\_keymap&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13948&nbsp; 1 hp\_wmi  
> > > > > > snd\_hwdep&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13602&nbsp; 1 snd\_hda\_codec  
> > > > > > coretemp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13435&nbsp; 0   
> > > > > > snd\_pcm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 102040&nbsp; 3 snd\_hda\_codec\_hdmi,snd\_hda\_cod ec,snd\_hda\_intel  
> > > > > > kvm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 459872&nbsp; 0   
> > > > > > snd\_page\_alloc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18710&nbsp; 2 snd\_pcm,snd\_hda\_intel  
> > > > > > snd\_seq\_midi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13324&nbsp; 0   
> > > > > > joydev&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17332&nbsp; 0   
> > > > > > snd\_seq\_midi\_event&nbsp;&nbsp;&nbsp;&nbsp; 14899&nbsp; 1 snd\_seq\_midi  
> > > > > > crct10dif\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14250&nbsp; 0   
> > > > > > crc32\_pclmul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13113&nbsp; 0   
> > > > > > aesni\_intel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 55624&nbsp; 0   
> > > > > > aes\_x86\_64&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17131&nbsp; 1 aesni\_intel  
> > > > > > lrw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13286&nbsp; 1 aesni\_intel  
> > > > > > snd\_rawmidi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 30682&nbsp; 1 snd\_seq\_midi  
> > > > > > gf128mul&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14951&nbsp; 1 lrw  
> > > > > > glue\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13990&nbsp; 1 aesni\_intel  
> > > > > > ablk\_helper&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13597&nbsp; 1 aesni\_intel  
> > > > > > cryptd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 20359&nbsp; 2 aesni\_intel,ablk\_helper  
> > > > > > drm&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 303102&nbsp; 2 nvidia  
> > > > > > serio\_raw&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13413&nbsp; 0   
> > > > > > 
> > > > > > snd\_seq&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 61567&nbsp; 2 snd\_seq\_midi\_event,snd\_seq\_mid i  
> > > > > > snd\_seq\_device&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 14497&nbsp; 3 snd\_seq,snd\_rawmidi,snd\_seq\_mi di  
> > > > > > 
> > > > > > snd\_timer&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 29500&nbsp; 2 snd\_pcm,snd\_seq  
> > > > > > parport\_pc&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32701&nbsp; 2   
> > > > > > snd&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 69367&nbsp; 21 snd\_hda\_codec\_realtek,snd\_hwde p,snd\_timer,snd\_hda\_codec\_hdmi ,snd\_pcm,snd\_seq,snd\_rawmidi, snd\_hda\_codec,snd\_hda\_intel, snd\_seq\_device,snd\_seq\_midi  
> > > > > > parport&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 42299&nbsp; 2 ppdev,parport\_pc  
> > > > > > shpchp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 37032&nbsp; 0   
> > > > > > soundcore&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12680&nbsp; 1 snd  
> > > > > > lpc\_ich&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 21080&nbsp; 0   
> > > > > > wmi&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19177&nbsp; 1 hp\_wmi  
> > > > > > tpm\_infineon&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 17372&nbsp; 0   
> > > > > > mac\_hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 13205&nbsp; 0   
> > > > > > hid\_generic&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 12548&nbsp; 0   
> > > > > > usbhid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 48514&nbsp; 0   
> > > > > > hid&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106148&nbsp; 2 hid\_generic,usbhid  
> > > > > > e1000e&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 254433&nbsp; 0   
> > > > > > ahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 34091&nbsp; 1   
> > > > > > psmouse&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 106643&nbsp; 0   
> > > > > > ptp&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 18933&nbsp; 1 e1000e  
> > > > > > libahci&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 32716&nbsp; 1 ahci  
> > > > > > pps\_core&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 19333&nbsp; 1 ptp  
> > > > > >   
> > > > > >   
> > > > > > 
> > > > > > see anything suspicious?  
> > > > > > 
> > > > > >   
> > > > > > 
> > > > > >   
> > > > > > 
> > > > > > > > On Tue, Oct 11, 2016 at 5:49 PM, [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\> wrote:  
> > > > > > > > 
> > > > > > > > > &nbsp;
> > > > > > > > > 
> > > > > > > > > Thanks for the info! Hopefully this won't be needed in the future anymore:  
> > > > > > > > >   
> > > > > > > > > I've changed ptb for the next beta to execute update-initramfs as required. I've also updated the blacklist-psychtoolbox.conf file to blacklist the lp module harder, so hopefully it won't be neccessary to modify any of the files you described anymore. At least on my Ubuntu 14.04.5-LTS machine this reliably disabled lp after a run of PsychLinuxConfiguration + Reboot.  
> > > > > > > > >   
> > > > > > > > > The file now looks like this, with the new redirection of lp to /bin/false:  
> > > > > > > > >   
> > > > > > > > > # Blacklist the lp modules for parallel port line printers.  
> > > > > > > > > # It would prevent exclusive use of ppdev for low-level  
> > > > > > > > > # parallel port access by Psychtoolbox.  
> > > > > > > > > blacklist lp  
> > > > > > > > > install lp /bin/false  
> > > > > > > > >   
> > > > > > > > > Btw., apart from the fact that PsychLinuxConfiguration does this for you automatically, if you had to do it manually, you wouldn't edid the /etc/groups file by hand. Look at PsychLinuxConfiguration.m for how this is done properly - and safely via the:  
> > > > > > > > >   
> > > > > > > > > sudo usermod -a -G lp myusername  
> > > > > > > > >   
> > > > > > > > > command to add user myusername to group 'lp'.  
> > > > > > > > >   
> > > > > > > > > best,  
> > > > > > > > > -mario
> > > > > > > > 
> > > > > > > >   
> > > > > > > >   
> > > > > > > >   
> > > > > > > > --   
> > > > > > > > 
> > > > > > > > Jonathan Folstein  
> > > > > > > > Assistant Professor  
> > > > > > > > Department of Psychology  
> > > > > > > > Florida State University   
> > > > > > > > 1107 W. Call St.   
> > > > > > > > Tallahassee, FL 32306-4301
> > > > > > > > office: 850-645-0654  
> > > > > > > > 
> > > > > > > > fax: 850-644-7739
> > > > > > > > [folstein@...](mailto:folstein@...)
> > > > > 
> > > > >   
> > > > >   
> > > > >   
> > > > > --   
> > > > > 
> > > > > Jonathan Folstein  
> > > > > Assistant Professor  
> > > > > Department of Psychology  
> > > > > Florida State University   
> > > > > 1107 W. Call St.   
> > > > > Tallahassee, FL 32306-4301
> > > > > office: 850-645-0654  
> > > > > 
> > > > > fax: 850-644-7739
> > > > > 
> > > > > [folstein@...](mailto:folstein@...)
> > > > 
> > > >   
> > > >   
> > > >   
> > > > --   
> > > > 
> > > > Jonathan Folstein  
> > > > Assistant Professor  
> > > > Department of Psychology  
> > > > Florida State University   
> > > > 1107 W. Call St.   
> > > > Tallahassee, FL 32306-4301
> > > > office: 850-645-0654  
> > > > 
> > > > fax: 850-644-7739
> > > > [folstein@...](mailto:folstein@...)
> > 
> >   
> >   
> >   
> > --   
> > 
> > Jonathan Folstein  
> > Assistant Professor  
> > Department of Psychology  
> > Florida State University   
> > 1107 W. Call St.   
> > Tallahassee, FL 32306-4301
> > office: 850-645-0654  
> > 
> > fax: 850-644-7739
> > [folstein@...](mailto:folstein@...)