Re: 5.0.0-rc3 : Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries

Re: 5.0.0-rc3 : Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries

[Philippe Mathieu-Daudé]

Hi Dennis,

On 4/17/20 2:42 AM, Dennis Clarke via wrote:>
> Very strange messages from qemu 5.0.0-rc3 wherein I try to run :
>
> $ /usr/local/bin/qemu-system-ppc64 --version
> QEMU emulator version 4.2.93
> Copyright (c) 2003-2020 Fabrice Bellard and the QEMU Project developers
> $
> $
> $ /usr/local/bin/qemu-system-ppc64 \
>  > -machine pseries-4.1 -cpu power9 -smp 4 -m 12G -accel tcg \
>  > -drive file=/home/ppc64/ppc64le.qcow2 \
>  > -device virtio-net-pci,netdev=usernet \
>  > -netdev user,id=usernet,hostfwd=tcp::10000-:22 \
>  > -serial stdio -display none -vga none
> qemu-system-ppc64: warning: TCG doesn't support requested feature,
> cap-cfpc=workaround
> qemu-system-ppc64: warning: TCG doesn't support requested feature,
> cap-sbbc=workaround
> qemu-system-ppc64: warning: TCG doesn't support requested feature,
> cap-ibs=workaround[...]> Quiescing Open Firmware ...
> Booting Linux via __start() @ 0x0000000002000000 ...
> Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries
[...]

Thanks for this report. I purposed a patch to fix this, but don't expect
it to be fixed in the next 5.0 release because this is not a critical
security bug.

>  From this point onwards I see an endless stream of :
>
> Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries
> Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries
> Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries
> Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries
> Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries
> Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries
[...]
>
> No idea what that is .. but it doesn't look friendly.
>
> Also I did compile qemu with --enable-debug --disable-strip and the
> performance is truely horrific.  I can only assume that those options
> are the cause. Any thoughts from anyone would be wonderful.

--enable-debug enables --enable-debug-tcg which is not designed for
performance. You might want to try '--enable-debug --disable-debug-tcg'.

Re: 5.0.0-rc3 : Opcode 1f 12 0f 00 (7ce003e4) leaked temporaries

[Richard Henderson]

On 4/17/20 2:20 AM, Philippe Mathieu-Daudé wrote:
> --enable-debug enables --enable-debug-tcg which is not designed for
> performance. You might want to try '--enable-debug --disable-debug-tcg'.

More importantly, --enable-debug turns off compiler optimization.  That is
going to be the biggest hit to performance.


r~