linux-kernel - Re: [tip:x86/mm] x86/mm/mtrr: Clean up mtrr_type

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Message-ID: <20150731152713.GA9756@nazgul.tnic>
Date:	Fri, 31 Jul 2015 17:27:13 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...nel.org, hpa@...or.com, dvlasenk@...hat.com, bp@...e.de,
	akpm@...ux-foundation.org, brgerst@...il.com, tglx@...utronix.de,
	linux-mm@...ck.org, luto@...capital.net, mcgrof@...e.com,
	toshi.kani@...com, torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/mm] x86/mm/mtrr: Clean up mtrr_type_lookup()

On Fri, Jul 31, 2015 at 05:08:06PM +0200, Peter Zijlstra wrote:
> But its things like set_memory_XX(), and afaict that's all buggy against
> MTRR modifications.

I think the idea is to not do any MTRR modifications at some point:

>From Documentation/x86/pat.txt:

"... Ideally mtrr_add() usage will be phased out in favor of
arch_phys_wc_add() which will be a no-op on PAT enabled systems. The
region over which a arch_phys_wc_add() is made, should already have been
ioremapped with WC attributes or PAT entries, this can be done by using
ioremap_wc() / set_memory_wc()."

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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