From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f172.google.com (mail-wi0-f172.google.com [209.85.212.172]) by kanga.kvack.org (Postfix) with ESMTP id 229BE6B00FE for ; Mon, 3 Nov 2014 12:14:51 -0500 (EST) Received: by mail-wi0-f172.google.com with SMTP id bs8so7104850wib.11 for ; Mon, 03 Nov 2014 09:14:50 -0800 (PST) Received: from Galois.linutronix.de (Galois.linutronix.de. [2001:470:1f0b:db:abcd:42:0:1]) by mx.google.com with ESMTPS id e17si9107941wiw.45.2014.11.03.09.14.50 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Mon, 03 Nov 2014 09:14:50 -0800 (PST) Date: Mon, 3 Nov 2014 18:14:37 +0100 (CET) From: Thomas Gleixner Subject: Re: [PATCH v4 1/7] x86, mm, pat: Set WT to PA7 slot of PAT MSR In-Reply-To: <1414450545-14028-2-git-send-email-toshi.kani@hp.com> Message-ID: References: <1414450545-14028-1-git-send-email-toshi.kani@hp.com> <1414450545-14028-2-git-send-email-toshi.kani@hp.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: hpa@zytor.com, mingo@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jgross@suse.com, stefan.bader@canonical.com, luto@amacapital.net, hmh@hmh.eng.br, yigal@plexistor.com, konrad.wilk@oracle.com On Mon, 27 Oct 2014, Toshi Kani wrote: > + } else { > + /* > + * PAT full support. WT is set to slot 7, which minimizes > + * the risk of using the PAT bit as slot 3 is UC and is > + * currently unused. Slot 4 should remain as reserved. This comment makes no sense. What minimizes which risk and what has this to do with slot 3 and slot 4? > + * > + * PTE encoding used in Linux: > + * PAT > + * |PCD > + * ||PWT PAT > + * ||| slot > + * 000 0 WB : _PAGE_CACHE_MODE_WB > + * 001 1 WC : _PAGE_CACHE_MODE_WC > + * 010 2 UC-: _PAGE_CACHE_MODE_UC_MINUS > + * 011 3 UC : _PAGE_CACHE_MODE_UC > + * 100 4 > + * 101 5 > + * 110 6 Well, they are still mapped to WB/WC/UC_MINUS .... > + * 111 7 WT : _PAGE_CACHE_MODE_WT > + */ > + pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) | > + PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, WT); > + } Thanks, tglx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org