Re: [Xenomai-help] POSIX skin/Blackfin: SIGSEGV when stracing or gdb'ing

[Philippe Gerum <rpm@xenomai.org>]

On Fri, 2009-07-24 at 18:30 +0200, Philippe Gerum wrote:
> On Fri, 2009-07-24 at 18:13 +0200, Kolja Waschk wrote:
> > Hi,
> > 
> > [On Blackfin uClinux 2.6.30 w/v2.5-rc2 with Philippe's patch from
> > yesterday, trying to run C or C++ FDPIC executables using the POSIX
> > skin]
> > 
> > When starting the example I recently posted (and a completely different
> > app, or even just an empty main(){return 0;} too) via "strace" or from
> > gdbserver, it segfaults almost immediately.
> > 
> > Unfortunately, I'm not able to make gdb break anywhere before this
> > happens. Therefore, I assume it happens before main().  The bfin trace
> > output shows that PC when it happened was at
> > libpthread/linuxthreads.old/signals.c:127 (uClibc __pthread_sigaction?)
> > 
> > These are the last instructions executed before the trap (last first)
> > 
> >     Source : <0xffa00740> { _trap + 0x1c } IF !CC JUMP
> > 10 Target : <0xffa00724> { _trap + 0x0 }
> >     Source : <0x00457846> [ /lib/libpthread.so.0 + 0x7846 ] 0x9153
> > 11 Target : <0x0045783a> [ /lib/libpthread.so.0 + 0x783a ]
> >     Source : <0x004578a2> [ /lib/libpthread.so.0 + 0x78a2 ] JUMP.S
> > 12 Target : <0x0045789a> [ /lib/libpthread.so.0 + 0x789a ]
> >     Source : <0x00457838> [ /lib/libpthread.so.0 + 0x7838 ] IF !CC JUMP
> >        (libpthread/linuxthreads.old/signals.c:125)
> > 13 Target : <0x004577fc> [ /lib/libpthread.so.0 + 0x77fc ]
> >        (libpthread/linuxthreads.old/internals.h:410)
> >     Source : <0xffa00cd6> { __common_int_entry + 0xde } RTI
> > 14 Target : <0xffa00c74> { __common_int_entry + 0x7c }
> >     Source : <0xffa01070> { _evt_system_call + 0x64 } JUMP.S
> > 15 Target : <0xffa01070> { _evt_system_call + 0x64 }
> >     Source : <0xffa00944> { _system_call + 0xe8 } RTS
> 
> Might be a stack related issue, bit no proof of it so far.
> 
> > 
> > As said, it happens with a source file consisting of only int main()
> > {return 0;} and a compiler invocation as simple as
> > 
> >   bfin-linux-uclibc-gcc -L/usr/xenomai/lib -lpthread_rt -pthread
> >      -Wl,@/usr/xenomai/lib/posix.wrappers main.c -o main
> > 
> > Any idea?
> 
> To eliminate toolchain/dist issues, here is the combo that works for me
> (commit numbers from the relevant git trees):
> 
> blackfin toolchain: ce79f3d5449c78877e66965584c55a132d73d4e1
> uclinux-dist: 2137ff7920b51643c5c84536fe99fe7c5904498a
> blackfin kernel: 015153eee3851d2c485a85814888f031f3794cf4
> 

Forgot to mention:

http://download.gna.org/adeos/patches/v2.6/blackfin/adeos-ipipe-2.6.30.1-blackfin.git-ed2e9479-1.11-00.patch
on top of the blackfin kernel, and
git://xenomai.org/xenomai-head.git
(.../xenomai-2.4.git would do as well, though).

> How far are you from this setup?
> 
> > 
> > Thanks!
> > Kolja
> > 
> > 
> > _______________________________________________
> > Xenomai-help mailing list
> > Xenomai-help@domain.hid
> > https://mail.gna.org/listinfo/xenomai-help
-- 
Philippe.