Re: [Qemu-ppc] [Qemu-devel] Segfault in block driver with qemu-system-ppc and -M mac99

[Andreas Färber]

Hi Mark,

Am 24.02.2013 13:08, schrieb Mark Cave-Ayland:
> Whilst running through some OpenBIOS tests, I came across the following
> segfault in qemu-system-ppc with -M mac99 on git master. It is
> consistently reproducible here with my test openSUSE image although
> strangely all my other images seem to run fine. The host is running
> amd64 Debian Wheezy.
> 
> 
> address@hidden:~/rel-qemu-git/bin$ gdb --args ./qemu-system-ppc -cdrom
> /home/build/src/qemu/image/ppc/openSUSE-11.1-NET-ppc.iso -boot d -g
> 1024x768x32 -vnc :1 -m 512 -M mac99
> GNU gdb (GDB) 7.4.1-debian
> Copyright (C) 2012 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-linux-gnu".
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>...
> Reading symbols from /home/build/rel-qemu-git/bin/qemu-system-ppc...done.
> (gdb) handle SIGUSR1 nostop noprint
> Signal        Stop      Print   Pass to program Description
> SIGUSR1       No        No      Yes             User defined signal 1
> (gdb) run
> Starting program: /home/build/rel-qemu-git/bin/qemu-system-ppc -cdrom
> /home/build/src/qemu/image/ppc/openSUSE-11.1-NET-ppc.iso -boot d -g
> 1024x768x32 -vnc :1 -m 512 -M mac99
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
> [New Thread 0x7fffdf197700 (LWP 17230)]
> [New Thread 0x7fffde996700 (LWP 17231)]
> [New Thread 0x7fffbc9e8700 (LWP 17232)]
> [Thread 0x7fffdf197700 (LWP 17230) exited]
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x00005555555ef458 in bdrv_co_do_readv (bs=0x0, sector_num=169,
> nb_sectors=0, qiov=0x55555661f878, flags=0) at block.c:2240
> 2240        BlockDriver *drv = bs->drv;
> (gdb) bt
> #0  0x00005555555ef458 in bdrv_co_do_readv (bs=0x0, sector_num=169,
> nb_sectors=0, qiov=0x55555661f878, flags=0) at block.c:2240
> #1  0x00005555555f3a28 in bdrv_co_do_rw (opaque=0x555556620030) at
> block.c:3837
> #2  0x0000555555631fa4 in coroutine_trampoline (i0=1448744496, i1=21845)
> at coroutine-ucontext.c:138
> #3  0x00007ffff508c020 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
> #4  0x00007fffffffb100 in ?? ()
> #5  0x0000000000000000 in ?? ()
> (gdb)
> 
> 
> It seems as if the BlockDriver pointer is coming back as NULL - does
> anyone have any ideas as to what could be causing this?

Have you tried a revision before my macio refactoring? It changed which
IDE code paths are taken.

Cheers,
Andreas

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