linux-kernel - Re: [PATCH] x86, setup: add __flush

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Message-ID: <54252756.6000001@nexus-software.ie>
Date:	Fri, 26 Sep 2014 09:44:06 +0100
From:	Bryan O'Donoghue <pure.logic@...us-software.ie>
To:	Dave Hansen <dave.hansen@...el.com>,
	Ong Boon Leong <boon.leong.ong@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
CC:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	Arjan van de Ven <arjan@...ux.intel.com>
Subject: Re: [PATCH] x86, setup: add __flush_tlb() for Intel Quark X1000

On 26/09/14 06:32, Dave Hansen wrote:
> I'd just say:
>
> Quark X1000 wrongly advertises PGE.  Work around this with an
> unconditional full flush using a CR3 write instead of CR4.PGE:

Hi Dave.

In another thread with Ingo Molnar and Henrique de Moraes Holschuh the 
following text was proposed.

+	/*
+	 * Locate the page directory and flush the TLB.
+	 *
+	 * On Quark X1000 CPUs we still have the PGE bit incorrectly set
+	 * due to a processor erratum, so __flush_tlb_all() is not yet
+	 * doing what it says.  Fortunately we have a cr3 flush here,
+	 * which is what is needed in this processor to flush TLBs, so
+	 * there's no need to add a Quark X1000 quirk here.
+	 *
+	 * early_init_intel will unset the X86_FEATURE_PGE flag later
+	 * and __flush_tlb_all() will flush via cr3
+	 */

Path submitted as "[PATCH] x86: Quark: Comment setup_arch for TLB/PGE 
bugfix"

Does that work for you ?

--
BOD
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