Re: [Qemu-devel] bug in popcnt emulation with some register operand(s)?

[Andriy Gapon]

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.

> 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