Re: [Xenomai] segfault using rt_printf service

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On 09/14/2012 04:33 PM, Alessio Margan @ IIT wrote:
> Hi all,
> 
> I'm switching from xenomai 2.5.6 to 2.6.1 using 
> adeos-ipipe-2.6.38.8-x86-2.11-01.patch
> In this test I have 2 threads :
> - rx_udp receive udp packets from dsp boards at 1kHz
> - boards_test send udp packets at 1kHz
> 
> I got segfault in printer_loop thread, the point is that if I change env 
> var RT_PRINT_PERIOD to about 10 or 1000 (default is 100 ms) I do not 
> have segfault.
> 
> Any suggestion ?
> 
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0xb7d1ab70 (LWP 5998)]
> 0xb7d7cb0c in fwrite () from /lib/i686/cmov/libc.so.6
> (gdb) bt
> #0  0xb7d7cb0c in fwrite () from /lib/i686/cmov/libc.so.6
> #1  0xb7fccbf9 in print_buffers () from /usr/xenomai/lib/libxenomai.so.0
> #2  0xb7fcd867 in printer_loop () from /usr/xenomai/lib/libxenomai.so.0
> #3  0xb7fb5955 in start_thread () from /lib/i686/cmov/libpthread.so.0
> #4  0xb7dec5ee in clone () from /lib/i686/cmov/libc.so.6

Since you seem to be able to catch the error with gdb, maybe try and
understand the reason for the segfault? The first, quick check, is to
type "info register", type cat /proc/pid/maps in another terminal, and
check that the stack pointer is in a valid mapping, to check if we do
not have a stack overflow.

If you fail to find the error, please try and reduce the test program to
a simple test case, as simple as needed for the bug to happen and post
it on this mailing list, this would allow us to reproduce the issue.

-- 
					    Gilles.