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Date: Fri, 10 Nov 2000 11:55:03 -0800
From: "H. Peter Anvin" <hpa@transmeta.com>
Organization: Transmeta Corporation
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To: davej@suse.de
CC: Brian Gerst <bgerst@didntduck.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [Fwd: CPU detection revamp (Request for comments)]
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davej@suse.de wrote:

> On Fri, 10 Nov 2000, Brian Gerst wrote:
> 
> > > features        : fpu vme de pse tsc msr mce cx8 pge mmx syscall 3dnow
> >
> > The K6's don't support sysenter/sysexit.
> 
> The K6 datasheets suggests otherwise.
> Some models seem to have sysenter/sysexit, whilst others have
> syscall/sysret. No model seems to have both.

Athlons have both.  Since the ext-bit 10 stuff is useless, I haven't
bothered reporting it at all.

> The datasheets are somewhat confusing, as it doesn't mention bit 10
> at all, just an oversized box for bit 11.
> 
> > It really should have been marked differently before.
> 
> Before we weren't mentioning it at all, look..
> flags  : fpu vme de pse tsc msr mce cx8 sep mtrr pge mmx 3dnow
> 
> > The early K6's used extended bit 10 to indicate syscall/sysret
> > capabality, but this version has some quirks that make it pretty much
> > unusable.  Later K6's use extended bit 11 to indicate syscall/sysret.
> 
> And where does sysenter/sysexit fit in?

sysenter/sysexit is the "sep" feature.

	-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
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