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Date: Wed, 18 Dec 2002 12:14:14 -0800
From: "H. Peter Anvin" <hpa@transmeta.com>
Organization: Transmeta Corporation
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To: Terje Eggestad <terje.eggestad@scali.com>
CC: Linus Torvalds <torvalds@transmeta.com>,
       Ulrich Drepper <drepper@redhat.com>,
       Matti Aarnio <matti.aarnio@zmailer.org>,
       Hugh Dickins <hugh@veritas.com>, Dave Jones <davej@codemonkey.org.uk>,
       Ingo Molnar <mingo@elte.hu>,
       linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Intel P6 vs P7 system call performance
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Terje Eggestad wrote:
> what about:
> 
> int (*_vsyscall) (int, ...);
> _vsyscall = mmap(NULL, getpagesize(),  PROT_READ|PROT_EXEC,
> MAP_VSYSCALL, , ); 
> 
> or if you're afraid of running out of MAP_* flags:
> 
> fd = open("/dev/vsyscall", );
> _vsyscall = mmap(NULL, getpagesize(),  PROT_READ|PROT_EXEC, MAP_SHARED,
> fd, 0);
> 
> Then you can leisurely map it in just after the programs text segment. 
> 

Very ugly -- then the application has to do indirect calls.

	-hpa


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