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<== Date ==> <== Thread ==>

Subject: EPICS and interruptable system calls
From: "Mark Rivers" <rivers@cars.uchicago.edu>
To: "Eric Norum" <norume@aps.anl.gov>, "Andrew Johnson" <anj@aps.anl.gov>
Cc: Core-Talk <Core-Talk@aps.anl.gov>
Date: Fri, 30 Jan 2009 12:30:27 -0600

Eric and Andrew,

 

According to this message from Prosilica they are simply using the the new POSIX Timer API provided in librt.so.  I’ve looked at the documentation for this, and indeed the default for the timers is to use SIGALRM, and indeed if one uses this library then all system calls need to be restarted if they terminate with EINTR.

 

I realize this is a big job, but it seems to me that allowing the use of the POSIX Timer API within EPICS applications is actually a very good idea.  I have made the minor change to epicsThreadSleep in libCom/osi/os/posix/osdThread.c, and it now works fine when the Prosilica driver is initialized and thus SIGALRM signals are happening frequently.  I am not sure how many other system calls in EPICS base would need to be changed.  I found, for example, that disk I/O I am doing in the areaDetector application, using the netCDF library, seems to work fine.  They do not appear to be retrying if write() fails.  The documentation in the link below says that record-oriented I/O will never return partial data and hence not need to be retried.

 

If the epicsTimer were changed to use that API would it be possible to get timer resolution better than, for example, the 0.01 second that Linux now provides?

 

Mark

 

 


From: Arlin Kalenchuk [mailto:akalenchuk@prosilica.com]
Sent: Thursday, January 29, 2009 3:06 PM
To: Mark Rivers
Cc: Eric Norum; Andrew Johnson; John M. Skinner
Subject: RE: More information

 

Hello Mark,

 

The last version we sent you should be able to find the camera ... It is the version you should be using to avoid the seg-fault issues you have encountered.

 

We do not use any signal in the driver, aside from SIGALRM which is use by the POSIX Timer API (librt.so). As a result of this, you really should be protecting EVERY system call that can be interrupted by a signal (usually stated in the call's documentation). This can be done as shown in the version of epicsThreadSleep() we sent earlier, or by using the macro TEMP_FAILURE_RETRY:

 

http://www.gnu.org/software/libtool/manual/libc/Interrupted-Primitives.html

 

The flag SA_RESTART is unfortunately not respected by all system calls, if at all on Linux.

 

I understand that rewriting your code isn’t an attractive option. We'd be more than happy to get rid of the POSIX Timer API we are using, however we aren’t aware of any suitable substitute. If you know of something, we'd love to hear about it.

 

------------------------------------------------

Arlin Kalenchuk

Prosilica Inc.

101 - 3750 North Fraser Way

Burnaby, BC, Canada, V5J 5E9

Tel: 604-875-8855 ext 124

Fax: 604-875-8856

www.prosilica.com


From: Mark Rivers [mailto:rivers@cars.uchicago.edu]
Sent: Thursday, January 29, 2009 11:57 AM
To: Arlin Kalenchuk
Cc: Eric Norum; Andrew Johnson; John M. Skinner
Subject: More information

 

Dear Arlin,

 

I have now done some more tests.  I modified epicsThreadSleep() as you suggested, so that it retries if it failed.

 

My driver and other parts of EPICS are the same as for the previous results I sent, i.e. I am waiting 5 seconds 3 times in my driver, and I am not installing any signal handler for SIGALRM in EPICS channel access in base.

 

Here is the result with your new version of libPvAPI.a

 

prosilicaConfig("PS1", 101271, 50, 200000000)

2009/01/29 13:37:18.846 Calling epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 13:37:23.846 Return from epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 13:37:23.848 Calling epicsThreadSleep for 5 seconds after calling PvInitialize()

2009/01/29 13:37:30.835 Return from epicsThreadSleep for 5 seconds after calling PvInitialize()

Called siginterrupt, status=0

2009/01/29 13:37:30.835 Calling epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

2009/01/29 13:37:35.835 Return from epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

2009/01/29 13:37:35.843 prosilica:connectCamera: Cannot find camera 101271

prosilica:prosilica: cannot connect to camera 101271, manually connect when available.

 

Note that the call to epicsThreadSleep now takes 5.0, 7.0 and 5.0 seconds the 3 times I call it.  Before modifying epicsThreadSleep it was only 1ms on the last 2 calls.

 

However, this does not fix the problem of not finding the camera.  It is not finding the camera, which is available.

 

I then simply relinked my application with the Oct. 3. version of libPvAPI.a.  It produces the following output:

 

prosilicaConfig("PS1", 101271, 50, 200000000)

2009/01/29 13:45:02.143 Calling epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 13:45:07.143 Return from epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 13:45:07.145 Calling epicsThreadSleep for 5 seconds after calling PvInitialize()

2009/01/29 13:45:12.145 Return from epicsThreadSleep for 5 seconds after calling PvInitialize()

Called siginterrupt, status=0

2009/01/29 13:45:12.145 Calling epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

2009/01/29 13:45:17.145 Return from epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

asynSetTraceIOMask("PS1",0,2)

 

The old version of the driver works fine.  Each call to epicsThreadSleep waits for 5.0 seconds as it should. It finds the camera, and I can control the camera fine.

 

With this version of the driver I also ran my file saving plugin.  I was able to stream 1000 frames to disk at 50 frames/second, for a total of 348MB.  So perhaps my worries about read() and write() function calls being interrupted and not completing correctly are unfounded?  Can you tell me if this is true, do I need to worry about those calls failing because of your drivers use of signals?  Exactly what Linux system calls do I need to retry if I use your driver in my application?

 

The readline library still does not work correctly. It does not output a newline between commands and command line recall does not work.

 

Bottom line:  I can make the old version of the library work (with significant issues), but the new version of the library will not find the camera.

 

Thanks,

Mark

 


From: Mark Rivers
Sent: Thursday, January 29, 2009 1:33 PM
To: 'Arlin Kalenchuk'
Cc: 'Eric Norum'; 'Andrew Johnson'; 'John M. Skinner'
Subject: RE: EPICS

 

I just did a Google search on readline and SIGALRM.  Readline does by default install a signal handler for SIGALRM:

 

http://www.delorie.com/gnu/docs/readline/rlman_43.html

 

 

2.5 Readline Signal Handling

Signals are asynchronous events sent to a process by the Unix kernel, sometimes on behalf of another process. They are intended to indicate exceptional events, like a user pressing the interrupt key on his terminal, or a network connection being broken. There is a class of signals that can be sent to the process currently reading input from the keyboard. Since Readline changes the terminal attributes when it is called, it needs to perform special processing when such a signal is received in order to restore the terminal to a sane state, or provide application writers with functions to do so manually.

Readline contains an internal signal handler that is installed for a number of signals (SIGINT, SIGQUIT, SIGTERM, SIGALRM, SIGTSTP, SIGTTIN, and SIGTTOU). When one of these signals is received, the signal handler will reset the terminal attributes to those that were in effect before readline() was called, reset the signal handling to what it was before readline() was called, and resend the signal to the calling application. If and when the calling application's signal handler returns, Readline will reinitialize the terminal and continue to accept input. When a SIGINT is received, the Readline signal handler performs some additional work, which will cause any partially-entered line to be aborted (see the description of rl_free_line_state() below).

There is an additional Readline signal handler, for SIGWINCH, which the kernel sends to a process whenever the terminal's size changes (for example, if a user resizes an xterm). The Readline SIGWINCH handler updates Readline's internal screen size information, and then calls any SIGWINCH signal handler the calling application has installed. Readline calls the application's SIGWINCH signal handler without resetting the terminal to its original state. If the application's signal handler does more than update its idea of the terminal size and return (for example, a longjmp back to a main processing loop), it must call rl_cleanup_after_signal() (described below), to restore the terminal state.

Readline provides two variables that allow application writers to control whether or not it will catch certain signals and act on them when they are received. It is important that applications change the values of these variables only when calling readline(), not in a signal handler, so Readline's internal signal state is not corrupted.

Variable: int rl_catch_signals

If this variable is non-zero, Readline will install signal handlers for SIGINT, SIGQUIT, SIGTERM, SIGALRM, SIGTSTP, SIGTTIN, and SIGTTOU.

The default value of rl_catch_signals is 1.

 

Mark

 

 


From: Mark Rivers
Sent: Thursday, January 29, 2009 1:06 PM
To: 'Arlin Kalenchuk'
Cc: 'Eric Norum'; 'Andrew Johnson'; 'John M. Skinner'
Subject: RE: EPICS

 

Dear Arlin,

 

I am making some real progress in getting the Prosilica cameras running under Linux.  I now have a configuration which allows me to reliably start my application, connnect to the camera and read frames.  However, there are some side-effects that we really need to work out.

 

The first problem is the one I mentioned in my previous message:  a call to PvInitialize appears to result in a call to siginterrupt(SIGALRM, 1)  or the equivalent.  This means that all “slow” system calls such as nanosleep(), read(), write(), etc. can return prematurely and need to be retried.  I really don’t think it is an option to rewrite all of EPICS to look for all system calls that could be interrupted and retry them.

 

My first set of tests is with the old (Oct.3 2008) version of the driver.

 

I modified my driver temporarily to the following to do 3 things:

 

1)       Do an epicsThreadSleep(5) before I call PvInitialize().  It works as expected.

2)       Do an epicsThreadSleep(5) after calling PvInitialize().  It returns in 1.0 second, not 5.0.

3)       Call siginterrupt(SIGALRM, 0) to turn off interruptable system calls, and then call epicsThreadSleep(5) again.  To my surprise it still returns in 1.0 or 2.0 seconds, not 5.0 seconds.  I don’t understand this.

 

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Calling epicsThreadSleep for 5 seconds before calling PvInitialize()\n");

    epicsThreadSleep(5.);

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Return from epicsThreadSleep for 5 seconds before calling PvInitialize()\n");

    if (!PvApiInitialized) {

        status = PvInitialize();

        if (status) {

            printf("%s:%s: ERROR: PvInitialize failed for camera %d, status=%d\n",

            driverName, functionName, uniqueId, status);

            return;

        }

        PvApiInitialized = 1;

    }

   

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Calling epicsThreadSleep for 5 seconds after calling PvInitialize()\n");

    epicsThreadSleep(5.);

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Return from epicsThreadSleep for 5 seconds after calling PvInitialize()\n");

 

#ifdef linux

    /* Try changing the siginterrupt to not interrupt system calls */

    status = siginterrupt(SIGALRM, 0);

    printf("Called siginterrupt, status=%d\n", status);

#endif

   

    /* It appears to be necessary to wait a little for the PvAPI library to find the cameras */

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Calling epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()\n");

    epicsThreadSleep(5.);

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Return from epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()\n");

   

    /* Try to connect to the camera. 

     * It is not a fatal error if we cannot now, the camera may be off or owned by

     * someone else.  It may connect later. */

    status = connectCamera();

 

Here is the output when I start my application:

 

prosilicaConfig("PS1", 101271, 50, 200000000)

2009/01/29 12:27:22.357 Calling epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 12:27:27.357 Return from epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 12:27:27.359 Calling epicsThreadSleep for 5 seconds after calling PvInitialize()

2009/01/29 12:27:28.359 Return from epicsThreadSleep for 5 seconds after calling PvInitialize()

Called siginterrupt, status=0

2009/01/29 12:27:28.359 Calling epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

2009/01/29 12:27:30.359 Return from epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

 

Note that the second 2 calls to epicsThreadSleep returned in 1.0 and 2.0 seconds respectively, not 5.0 seconds.

 

The application connected to the camera and exchanged some information, but still crashed with a segfault.

 

The traceback showed that a signal handler in EPICS base was being called, and then calling your driver function.

 

I then modified EPICS base to remove the calls to install our handler for SIGALRM (which simply calls any preexisting handler).  I was told that on Linux EPICS does not actually generate any SIGALRM signals.  I removed 2 calls to epicsSignalInstallSigAlarmIgnore() in the EPICS channel access code.  Once I did that my application runs OK, and can control the camera, read frames, etc.

 

I believe I may understand that problem.  Once I removed the calls to  epicsSignalInstallSigAlarmIgnore() it appears that the readline library is no longer working:  it does not insert newlines when I type Enter, and command line recall no longer works.  I strongly suspect that the Linux readline library is using SIGALRM, and somehow that was interacting badly with your driver when had installed our own signal handler for SIGALRM.  Perhaps readline was generating a SIGALRM signal and then we were calling your driver when you did not expect it?

 

I then did the identical test but with my application linked with the new version of libPvAPI.a that you sent yesterday.

 

That version behaves very differently, as seen in this output:

 

2009/01/29 12:59:08.761 Calling epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 12:59:13.761 Return from epicsThreadSleep for 5 seconds before calling PvInitialize()

2009/01/29 12:59:13.762 Calling epicsThreadSleep for 5 seconds after calling PvInitialize()

2009/01/29 12:59:13.763 Return from epicsThreadSleep for 5 seconds after calling PvInitialize()

Called siginterrupt, status=0

2009/01/29 12:59:13.763 Calling epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

2009/01/29 12:59:13.763 Return from epicsThreadSleep for 5 seconds after calling PvInitialize() and siginterrupt()

2009/01/29 12:59:13.763 prosilica:connectCamera: Cannot find camera 101271

 

The first call to epicsThreadSleep(5) waits 5 seconds as expected.  But the next 2 calls to epicsThreadSleep(5) return in 1 msec or less.  This is not enough time for your library to find all the cameras, so it fails to find the camera.  It appears that the new version of your library is generating SIGALRM signals over 1000 times per second because the nanosleep() is always returning in 1msec or less.  Is this true?

 

So the bottom line is that I can make my application “work” with the old version of the library.  But it still has serious problems because EPICS is not going to function well if system calls like nanosleep(), read() and write() can be interrupted.

 

Is it possible to re-write your driver so that it does not call siginterrupt(SIGALRM, 1)?  We can help provide code for timers or other functions if that is what is needed.

 

Thanks,

Mark

 


From: Mark Rivers
Sent: Thursday, January 29, 2009 12:07 PM
To: 'Arlin Kalenchuk'
Subject: RE: EPICS

 

Hi Arlin,

 

The problem is that EPICS has hundreds of calls to system functions that can be interrupted by signals such as SIGALRM, including read(), write(), etc.  It is simply not possible to change EPICS to be compatible with a call to:

 

siginterrupt(SIGARLM, 1);

 

That would require way too much modification to the tens of thousands of lines of code in EPICS.

 

Does your driver use a call to siginterrupt such as that above?

 

I have done some experimenting with adding a call to siginterrupt(SIGALRM, 0) after the call to PvInitialize().  However, this does not seem to fix the problem, it still seems to interrupt calls to nanosleep().  Do you repeatedly call siginterrupt()?

 

I have actually made a change to EPICS to remove our calls to catch SIGALRM signals.  That actually fixes the seg faults we were getting with the old version of the driver, and I can actually reliably collect images.  However, we don’t have an acceptable solution until we resolve the problem with interruptable system calls since calls to nanosleep will return too soon, calls to write() or read() may return without completing properly, etc.

 

I will send a more detailed message in a few minutes that explains what I have done and how it works better now.  I will also make tests with both your old library and the new version you sent yesterday.

 

Thanks,

Mark

 

 

 


From: Arlin Kalenchuk [mailto:akalenchuk@prosilica.com]
Sent: Thursday, January 29, 2009 11:26 AM
To: Mark Rivers
Subject: RE: EPICS

 

The POSIX function nanosleep() can be interrupted by a signal (such as SIGALRM which is used by the Linux timer API). When this occurs, the function will return -1 and errno will be set to EINTR. The epicsThreadSleep() function could be modified as follow:

 

epicsShareFunc void epicsShareAPI epicsThreadSleep(double seconds)

{

    struct timespec delayTime;

    struct timespec remainingTime;

    double nanoseconds;

 

    delayTime.tv_sec = (time_t)seconds;

    nanoseconds = (seconds - (double)delayTime.tv_sec) *1e9;

    delayTime.tv_nsec = (long)nanoseconds;

    while(nanosleep(&delayTime,&remainingTime) == -1)

        delayTime = remainingTime;

}

 

 

------------------------------------------------

Arlin Kalenchuk

Prosilica Inc.

101 - 3750 North Fraser Way

Burnaby, BC, Canada, V5J 5E9

Tel: 604-875-8855 ext 124

Fax: 604-875-8856

www.prosilica.com


From: Mark Rivers [mailto:rivers@cars.uchicago.edu]
Sent: Wednesday, January 28, 2009 4:41 PM
To: Arlin Kalenchuk
Subject: RE: EPICS

 

Hi Arlin,

 

Thanks for the quick response.

 

I untarred that file and linked my application with the following library from it.

 

-rw-r--r-- 1 epics epics 2300264 Jan 28 16:14 PvAPI1.19.3/lib-pc/x86/4.2/libPvAPI.a

 

The behavior is different, it does not consistently crash.  But it still does not work correctly.  It is not finding the camera, because the epicsThreadSleep function we are using is not working correctly when linked with your library.  

 

My code does the following.

 

   /* Initialize the Prosilica PvAPI library

    * We get an error if we call this twice, so we need a global flag to see if

    * it's already been done.*/

    if (!PvApiInitialized) {

        status = PvInitialize();

        if (status) {

            printf("%s:%s: ERROR: PvInitialize failed for camera %d, status=%d\n",

            driverName, functionName, uniqueId, status);

            return;

        }

        PvApiInitialized = 1;

    }

 

    /* It appears to be necessary to wait a little for the PvAPI library to find the cameras */

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Sleeping for 20 seconds\n");

    epicsThreadSleep(20.0);

asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR, "Done sleeping for 20 seconds\n");

 

    /* Try to connect to the camera.

     * It is not a fatal error if we cannot now, the camera may be off or owned by

     * someone else.  It may connect later. */

    status = connectCamera();

 

In the normal version of this code the call to epicsThreadSleep() is for 0.2 seconds (not 20 seconds), and it does not print the messages.  That 0.2 second delay is always sufficient (on Windows) to allow your code to have found the cameras.

 

I changed it to 20 seconds just to prove that it is not sleeping at all!  My code now prints out the message “Sleeping for 20 seconds”, but in fact it does not sleep it all, it immediately goes to the next statement and calls connectCamera(), which fails.  

 

There must be something that your library is doing which causes the epicsThreadSleep() function to return prematurely under Linux.

 

Here is the output when I run my program.  As shown by the timestamps on these messages, there is only 6 milliseconds between the message “Sleeping for 20 seconds” and the “Done sleeping for 20 second seconds” message, so the epicsThreadSleep command is returning immediately and connectCamera() is failing.

 

prosilicaConfig("PS1", 101271, 50, 200000000)

2009/01/28 18:00:07.462 Sleeping for 20 seconds

2009/01/28 18:00:07.468 Done sleeping for 20 seconds

2009/01/28 18:00:09.463 prosilica:connectCamera: Cannot find camera 101271

 

 

When I execute this modified version of my driver on Windows it works fine, and I get the following.  It sleeps for 20 seconds, and does not get an error trying to connect to the camera.

 

prosilicaConfig("PS1", 101271, 50, 200000000)

2009/01/28 18:04:45.640 Sleeping for 20 seconds

2009/01/28 18:05:05.641 Done sleeping for 20 seconds

asynSetTraceIOMask("PS1",0,2)

 

On Posix platforms (e.g. Linux) EPICS uses the following code to implement epicsThreadSleep()

 

epicsShareFunc void epicsShareAPI epicsThreadSleep(double seconds)

{

    struct timespec delayTime;

    struct timespec remainingTime;

    double nanoseconds;

 

    delayTime.tv_sec = (time_t)seconds;

    nanoseconds = (seconds - (double)delayTime.tv_sec) *1e9;

    delayTime.tv_nsec = (long)nanoseconds;

    nanosleep(&delayTime,&remainingTime);

}

 

So it looks like nanosleep is returning before the time has elapsed.

 

I then reverted back to the previous version of your library.  When I run that I get the following:

 

prosilicaConfig("PS1", 101271, 50, 200000000)

2009/01/28 17:55:30.547 Sleeping for 20 seconds

2009/01/28 17:55:31.547 Done sleeping for 20 seconds

asynSetTraceIOMask("PS1",0,2)

 

So it does not wait for 20 seconds, but it does wait for 1.0 seconds and it does find the camera.  The fact that it only sleeps for 1 second instead of 20 is obviously a problem, but at least it sleeps long enough to allow your code time to find the cameras.  But then it crashes later, after some communication with the camera, with the seg fault like I sent you previously.  Here is the backtrace from gdb:

 

(gdb) bt

#0  0x080f6753 in SIGAction ()

#1  0x0823d61d in ignoreSigAlarm (signal=14) at ../../../src/libCom/osi/os/posix/osdSignal.cpp:109

#2  <signal handler called>

#3  0x00110416 in __kernel_vsyscall ()

#4  0x002228ff in sigprocmask () from /lib/libc.so.6

#5  0x05ae08f7 in ?? () from /lib/libreadline.so.5

#6  <signal handler called>

#7  0x00110416 in __kernel_vsyscall ()

#8  0x002ce671 in select () from /lib/libc.so.6

#9  0x080f6b3e in pPvMultiplexer::Body ()

#10 0x080fa720 in _ThreadFunction ()

#11 0x003b932f in start_thread () from /lib/libpthread.so.0

#12 0x002d620e in clone () from /lib/libc.so.6

 

Mark

 


From: Arlin Kalenchuk [mailto:akalenchuk@prosilica.com]
Sent: Wednesday, January 28, 2009 4:40 PM
To: Mark Rivers
Subject: EPICS

 

Hello Mark,

 

Can you try running the attached engineering version of our latest driver? It should fix the issue you’re having. Let us know the results.

 

Thanks.

 

------------------------------------------------

Arlin Kalenchuk

Prosilica Inc.

101 - 3750 North Fraser Way

Burnaby, BC, Canada, V5J 5E9

Tel: 604-875-8855 ext 124

Fax: 604-875-8856

www.prosilica.com


From: Mark Rivers [mailto:rivers@cars.uchicago.edu]
Sent: Tuesday, January 27, 2009 1:23 PM
To: Arlin Kalenchuk
Subject: RE: EPICS

 

Dear Arlin,

 

I have not resolved the issue, it is still outstanding.

 

The customer you mention may be John Skinner from Brookhaven National Laboratory?  He got a Prosilica camera on trial, and hoped to use it with my EPICS software.  Unfortunately he had the same trouble I did, it would crash the program after initial successful communication with the camera.  This really looks like a problem with Linux signals being used both by EPICS and by your driver.

 

There are a lot of potential Prosilica users who want to run my EPICS software under Linux.  My software works fine on Windows, but crashes on Linux.  My code is identical in terms of how it communicates with your driver in both cases.

 

Thanks,

Mark

 

 


From: Arlin Kalenchuk [mailto:akalenchuk@prosilica.com]
Sent: Tuesday, January 27, 2009 2:51 PM
To: Mark Rivers
Subject: EPICS

 

Hello Mark,

 

A customer recently contacted us, who apparently is running into the same problems you had running our GigE series cameras with EPICS. Paul Kozik forwarded me your email correspondence, but it seems to me nobody got back to you after a Dec 18th email:

 

Paul,

 

While most of the time the backtrace is the one I sent previously, ocassionally it is as follows:

 

(gdb) bt

#0  0x0808ce33 in SIGAction ()

#1  0x0821bf4d in ignoreSigAlarm (signal=14) at

../../../src/libCom/osi/os/posix/osdSignal.cpp:109

#2  <signal handler called>

#3  0x00110416 in __kernel_vsyscall ()

 

Have you managed to resolve this issue, or is it still outstanding?

 

Thanks,

 

------------------------------------------------

Arlin Kalenchuk

Prosilica Inc.

101 - 3750 North Fraser Way

Burnaby, BC, Canada, V5J 5E9

Tel: 604-875-8855 ext 124

Fax: 604-875-8856

www.prosilica.com

 


Replies:
Re: EPICS and interruptable system calls Eric Norum

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