linux-kernel - Re: 2.6.26, PAT and AMD family 6

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Message-ID: <20080507230254.GL18516@elf.ucw.cz>
Date:	Thu, 8 May 2008 01:02:54 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	Yinghai Lu <yhlu.kernel@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Adrian Bunk <bunk@...nel.org>,
	Rene Herman <rene.herman@...access.nl>,
	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel <linux-kernel@...r.kernel.org>, hpa@...or.com,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org
Subject: Re: 2.6.26, PAT and AMD family 6

On Wed 2008-05-07 15:40:38, Yinghai Lu wrote:
> On Wed, May 7, 2008 at 3:37 PM, Pavel Machek <pavel@...e.cz> wrote:
> > On Wed 2008-05-07 15:22:37, Yinghai Lu wrote:
> >  > On Wed, May 7, 2008 at 3:14 PM, Pavel Machek <pavel@...e.cz> wrote:
> >  > >  3) copy&paste code remained in the patch
> >  >
> >  > i thought to keep the stub so could add more other stuff in the switch
> >  > like 64 bit
> >
> >  This is _not_ good enough reason to copy&paste. Just do it like this:
> >
> >
> >  >         switch (c->x86_vendor) {
> >  >         case X86_VENDOR_AMD:
> >  >                 early_init_amd(c);
> >
> > >                 break;
> >  >         case X86_VENDOR_INTEL:
> >  >                 early_init_intel(c);
> >
> > >                 break;
> >  >         case X86_VENDOR_CENTAUR:
> >  >                 early_init_centaur(c);
> >  >                 break;
> >  >         }
> >
> >  #         clear_cpu_cap(c, X86_FEATURE_PAT);
> >
> > #
> >  #         switch (c->x86_vendor) {
> >  #         case X86_VENDOR_AMD:
> >  #                if (c->x86 >= 0xf && c->x86 <= 0x11)
> >
> > #                         set_cpu_cap(c, X86_FEATURE_PAT);
> >  #                 break;
> >  #         case X86_VENDOR_INTEL:
> >  #                 if (c->x86 == 0xF || (c->x86 == 6 && c->x86_model >= 15))
> >
> > #                         set_cpu_cap(c, X86_FEATURE_PAT);
> >  #                 break;
> >  #         }
> >
> >  And then, factor out code marked # into separate function, and call it
> >  from all three places.
> 
> still need two copies or ifdef, otherwise you will check some 32bit
> only cpu fam/model in 64bit node.

So we'll check 32-bit only cpu in 64bit node. What is the problem?
Being microsecond slower during startup?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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