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Re: [Qemu-devel] bug in popcnt emulation with some register operand(s)?
From: |
Andriy Gapon |
Subject: |
Re: [Qemu-devel] bug in popcnt emulation with some register operand(s)? |
Date: |
Thu, 11 Oct 2012 00:03:50 +0300 |
User-agent: |
Mozilla/5.0 (X11; FreeBSD amd64; rv:15.0) Gecko/20120913 Thunderbird/15.0.1 |
on 08/10/2012 12:02 Andriy Gapon said the following:
> on 08/10/2012 10:52 malc said the following:
>> On Mon, 8 Oct 2012, Andriy Gapon wrote:
>>
>>>
>>> I am running Qemu (plain, no kvm, etc) on an AMD 10h machine that
>>> provides popcnt instruction. Qemu advertises availability of pocnt
>>> to a guest as well. What I see in the guest that popcnt
>>> 0x20(%r12),%r8 instruction actually placed its result into %rax.
>>> With %rdi and %rax operands the instruction worked fine though.
>>>
>>>
>>
>> Does following work?
>
> It does! Thank you very much.
Do you plan to commit this fix?
Is there anything that I should do to make that happen (sooner)?
>> diff --git a/target-i386/translate.c b/target-i386/translate.c
>> index e896abf..c36cc3e 100644
>> --- a/target-i386/translate.c
>> +++ b/target-i386/translate.c
>> @@ -7818,7 +7818,7 @@ static target_ulong disas_insn(DisasContext *s,
>> target_ulong pc_start)
>> goto illegal_op;
>>
>> modrm = cpu_ldub_code(cpu_single_env, s->pc++);
>> - reg = ((modrm >> 3) & 7);
>> + reg = ((modrm >> 3) & 7) | rex_r;
>>
>> if (s->prefix & PREFIX_DATA)
>> ot = OT_WORD;
>>
>
>
--
Andriy Gapon