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Re: [Qemu-devel] [Bug 600589] [NEW] xchg r8,rax treated as nop
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [Bug 600589] [NEW] xchg r8,rax treated as nop |
Date: |
Thu, 01 Jul 2010 09:17:10 -0700 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100621 Fedora/3.0.5-1.fc13 Thunderbird/3.0.5 |
On 07/01/2010 05:04 AM, Vic3Dexe wrote:
> Public bug reported:
>
> xchg r8,rax (49h 90h) executed as nop (90h) in long mode, in other words
> REX not used.
>
> qemu 0.12.4, host Win 7 x64, running qemu-system-x86_64.exe.
>
> ** Affects: qemu
> Importance: Undecided
> Status: New
>
Verified. Test case for x86_64-linux-user:
.globl main
.type main, @function
main:
movl $0, %r8d
movl $1, %eax
xchgq %r8, %rax
ret
Expected result is exit status 0.
r~