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[Qemu-devel] [Bug] qemu-system-ppc: "invalid/unsupported opcode" during
From: |
Stefan Weil |
Subject: |
[Qemu-devel] [Bug] qemu-system-ppc: "invalid/unsupported opcode" during debug session |
Date: |
Tue, 29 Dec 2009 16:09:17 +0100 |
User-agent: |
Mozilla-Thunderbird 2.0.0.22 (X11/20090707) |
Test environment:
* ppc-softmmu/qemu-system-ppc running on x86_64 host
* emulated ppc is running debian lenny
While debugging on the emulated ppc (each time when
a shared library is loaded after "r" command?),
qemu-system-ppc prints this error message:
invalid/unsupported opcode: 00 - 00 - 00 (00000000) 4800fa44 1
If logging is enabled, the error message goes to qemu.log:
IN:
0xc0013488: nop
0xc001348c: rlwinm r3,r3,0,0,19
0xc0013490: li r4,128
0xc0013494: mtctr r4
0xc0013498: mr r6,r3
0xc001349c: dcbst r0,r3
invalid/unsupported opcode: 00 - 00 - 00 (00000000) 4800fa44 1
IN:
0x4800fa40: twge r2,r2
0x4800fa44: .long 0x0
The debugger on the ppc system shows the "instruction"
which triggers the error message:
(gdb) disas
Dump of assembler code for function _dl_debug_state:
0x4800fa40 <_dl_debug_state+0>: blr
End of assembler dump.
(gdb) x 0x4800fa40
0x4800fa40 <_dl_debug_state>: 0x4e800020
(gdb) x/2x 0x4800fa40
0x4800fa40 <_dl_debug_state>: 0x4e800020 0x00000000
The unsupported opcode is 0, and it follows function
_dl_debug_state.
Debugging in an emulated system should not trigger
error messages on the host (denial-of-service).
Why does qemu try to interpret the word at 0x4800fa44?
Why does qemu show "twge r2,r2", not "blr"?
Regards
Stefan Weil
- [Qemu-devel] [Bug] qemu-system-ppc: "invalid/unsupported opcode" during debug session,
Stefan Weil <=