Re: [PATCH] x86-64: adjust ia32entry.S

From: Jan Beulich (JBeulich_at_novell.com)
Date: 11/11/05

  • Next message: Guido Guenther: "sparc64: Oops in pci_alloc_consistent with cingergyT2" 
    Date:	Fri, 11 Nov 2005 16:50:49 +0100
To: "Andi Kleen" <ak@suse.de>

    >>> Andi Kleen <ak@suse.de> 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
    incorrect
    >> 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
    adjustment.

    Jan
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