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Re: [Qemu-devel] Confusion regarding temporaries with branch conditional
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] Confusion regarding temporaries with branch conditional |
Date: |
Wed, 30 Nov 2016 09:03:21 -0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 11/30/2016 08:55 AM, Alex Bennée wrote:
>
> Nikunj A Dadhania <address@hidden> writes:
>
>> Hi,
>>
>> I was writing one instruction and hit following issue:
>>
>> [snip]/qemu/tcg/tcg.c:2039: tcg fatal error
>> qemu-ppc64le: [snip]/qemu/translate-all.c:175: tb_lock: Assertion
>> `!have_tb_lock' failed.
>> Segmentation fault (core dumped)
>
> This is confusing because something is trying to take the tb_lock while
> you are in code generation. tb_lock is held for code generation to
> ensure serialisation of generation.
Yes, I've seen this myself. I never got around to reporting the "problem"
properly. It's a confusing side effect of a SIGSEGV arriving during tcg code
generation. The signal handler longjmps back with unexpected locks held.
Probably we should simply crash earlier and less confusingly.
r~