Re: [PATCH] x86-64: adjust ia32entry.S
From: Jan Beulich (JBeulich_at_novell.com)
Date: Fri, 11 Nov 2005 16:50:49 +0100 To: "Andi Kleen" <email@example.com>
>>> Andi Kleen <firstname.lastname@example.org> 11.11.05 16:34:44 >>>
>On Wednesday 09 November 2005 17:10, Jan Beulich wrote:
>> IA32 compatibility entry points needlessly played with extended
>> registers. Additionally, frame unwind information was still
>> for ia32_ptregs_common (sorry, my fault).
>What do you mean with needlessly played? That it didn't initialize
>all on the stack frame? That was more a feature than a bug.
>Did it cause you problems?
It saved and restored R12-R15, even though these registers have no
meaning (and are architecturally undefined) when coming from/going to
32-bit mode. Problems? No, except that without the extra loads (stores
don't matter that much I believe) performance is better...
>In general I'm weary of making the asm macros more complex
>(adding more arguments etc.) Please keep it simple.
Then ignore this, perhaps with the exception of the unwind info
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