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Date: Tue, 17 Dec 2002 20:15:47 -0800 (PST)
From: Linus Torvalds <torvalds@transmeta.com>
To: Ulrich Drepper <drepper@redhat.com>
cc: Matti Aarnio <matti.aarnio@zmailer.org>, Hugh Dickins <hugh@veritas.com>,
       Dave Jones <davej@codemonkey.org.uk>, Ingo Molnar <mingo@elte.hu>,
       <linux-kernel@vger.kernel.org>, <hpa@transmeta.com>
Subject: Re: Intel P6 vs P7 system call performance
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On Tue, 17 Dec 2002, Linus Torvalds wrote:
>
> How about this diff? It does both the 6-parameter thing _and_ the
> AT_SYSINFO addition.

The 6-parameter thing is broken. It's clever, but playing games with %ebp
is not going to work with restarting of the system call - we need to
restart with the proper %ebp.

I pushed out the AT_SYSINFO stuff, but we're back to the "needs to use
'int $0x80' for system calls that take 6 arguments" drawing board.

The only sane way I see to fix the %ebp problem is to actually expand the
kernel "struct ptregs" to have separate "ebp" and "arg6" fields (so that
we can re-start with the right ebp, and have arg6 as the right argument on
the stack). That would work but is not really worth it.

		Linus


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