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Date: Thu, 12 Mar 2015 16:51:24 +0000
From: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
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Subject: Re: [Qemu-devel] qemu-system-ppc TCG assert with git master
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To: Richard Henderson <rth@twiddle.net>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, qemu-devel <qemu-devel@nongnu.org>, "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>



On 03/12/2015 03:41 PM, Richard Henderson wrote:
> On 03/12/2015 01:41 AM, Mark Cave-Ayland wrote:
>> Whilst testing git master in preparation for some OpenBIOS updates, I'm
>> seeing the following TCG assert in one of my older test images:
>>
>>
>> $ gdb --args ./qemu-system-ppc -cdrom
>> /home/build/src/qemu/image/ppc/ubuntu-5.10-live-powerpc.iso -boot d -g
>> 800x600x8
> Older, eh?  I can only find 5.04.  ;-)
>
> And, fwiw, that doesn't assert.  I get all the way to
>
> Kernel panic - not syncing: VFS: unable to mount root fs on unknown-block(1,0)
>
> So, I guess I need something different to
>
> http://cdimage.ubuntu.com/ubuntu-mate/daily-live/current/vivid-desktop-powerpc.iso
>
> to reproduce this.
>
>
>
> r~
>

Hi Richard,

I can reproduce it fine here with 
http://old-releases.ubuntu.com/releases/5.10/.
As far as I see it, the Instruction at 0xc9105830 generates a mov 0 to 
r30, which is optimized by tcg_opt_gen_mov and r30 is set to 
TCG_TEMP_CONST. When 0xc9105838 or r0, r30, r30 should be optimized r30 
is already in the state TCG_TEMP_CONST and the assert fails.

Cheers,
Bastian