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X-Authentication-Warning: eos.vss.fsi.com: ford owned process doing -bs
Date: Tue, 30 Dec 2003 15:45:18 -0600 (CST)
From: Brian Ford <ford AT vss DOT fsi DOT com>
X-X-Sender: ford AT eos
To: cygwin AT cygwin DOT com
Subject: Re: 1.5.6-pre: Occasional bad memory accesses within cygwin1.dll
In-Reply-To: <20031230214309.GA30386@redhat.com>
Message-ID: <Pine.GSO.4.58.0312301545010.23399@eos>
References: <010b01c3cd5a$a138c9b0$d6e28351 AT starfruit> <20031230033711 DOT GA20304 AT redhat DOT com> <Pine DOT GSO DOT 4 DOT 58 DOT 0312301428540 DOT 23399 AT eos> <20031230214309 DOT GA30386 AT redhat DOT com>
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On Tue, 30 Dec 2003, Christopher Faylor wrote:

> On Tue, Dec 30, 2003 at 02:36:12PM -0600, Brian Ford wrote:
> >On Mon, 29 Dec 2003, Christopher Faylor wrote:
> >
> >> On Sun, Dec 28, 2003 at 03:52:33PM -0000, Max Bowsher wrote:
> >> >I installed a self-built cygwin HEAD version - mostly it works fine, but it
> >> >causes odd failures during builds (speculation: race when many processes
> >> >being created and destroyed?)
> >> >
> >> >The most common failure is a Windows error box:
> >> >
> >> >The instruction at "0x6108621a" references memory at "0x610030b0". The
> >> >memory could not be written.
> >> >
> >> >(These addresses are constant.)
> >> >
> >> >$ addr2line -e /bin/cygwin1.dll 0x6108621a 0x610030b0
> >> >.../src/winsup/cygwin/shm.cc:331
> >> >.../src/winsup/cygwin/cygthread.cc:34
> >>
> >> This isn't too useful, unfortunately.  The line numbers are an artifact
> >> of the fact that there is no STABS information in the generated asm in
> >> 'sigfe.s'.  Can you get an assembly listing of the lines around this
> >> instruction?
> >>
> >I think this is the same problem.  It shows up all over the place for me
> >in the testsuite.
> >
> >$ env
> >GNU gdb 5.3
> >Copyright 2002 Free Software Foundation, Inc.
> >GDB is free software, covered by the GNU General Public License, and you are
> >welcome to change it and/or distribute copies of it under certain conditions.
> >Type "show copying" to see the conditions.
> >There is absolutely no warranty for GDB.  Type "show warranty" for details.
> >This GDB was configured as "i686-pc-cygwin"...
> >(gdb) r
> >Starting program:
> >/home/ford/downloads/cygb2/i686-pc-cygwin/winsup/testsuite/testsuite/checksignal.exe
> >
> >Program received signal SIGSEGV, Segmentation fault.
> >0x6108bcad in _sigfe ()
> >Current language:  auto; currently c++
> >(gdb) bt
> >#0  0x6108bcad in _sigfe ()
> >#1  0xffffffff in ?? ()
> >#2  0x00402b1f in cygwin_crt0 (f=0x401134 <main>)
> >    at ../../../../cygwin/winsup/cygwin/lib/cygwin_crt0.c:24
> >#3  0x0040103c in mainCRTStartup ()
> >#4  0x77f1bb7b in _system_dlls__ ()
> >(gdb) disassemble
> >Dump of assembler code for function _sigfe:
> >0x6108bc90 <_sigfe>:    push   %edx
> >0x6108bc91 <_sigfe+1>:  mov    %fs:0x4,%eax
> >0x6108bc97 <_sigfe+7>:  mov    $0x4,%edx
> >0x6108bc9c <_sigfe+12>: xadd   %edx,0xffffeff8(%eax)
> >0x6108bca3 <_sigfe+19>: lea    0x6108bcb1,%eax
> >0x6108bca9 <_sigfe+25>: xchg   %eax,0x8(%esp,1)
> >0x6108bcad <_sigfe+29>: mov    %eax,(%edx)
> >0x6108bcaf <_sigfe+31>: pop    %edx
> >0x6108bcb0 <_sigfe+32>: ret
> >End of assembler dump.
> >(gdb)
>
> $edx?
>
(gdb) p $edx
$1 = 0

-- 
Brian Ford
Senior Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
Phone: 314-551-8460
Fax:   314-551-8444

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