From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751364AbbHAQdQ (ORCPT ); Sat, 1 Aug 2015 12:33:16 -0400 Received: from mail.skyhub.de ([78.46.96.112]:48287 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750935AbbHAQdO (ORCPT ); Sat, 1 Aug 2015 12:33:14 -0400 Date: Sat, 1 Aug 2015 18:33:11 +0200 From: Borislav Petkov To: "Luis R. Rodriguez" Cc: Toshi Kani , Peter Zijlstra , mingo@kernel.org, hpa@zytor.com, dvlasenk@redhat.com, bp@suse.de, akpm@linux-foundation.org, brgerst@gmail.com, tglx@linutronix.de, linux-mm@kvack.org, luto@amacapital.net, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/mm] x86/mm/mtrr: Clean up mtrr_type_lookup() Message-ID: <20150801163311.GA15356@nazgul.tnic> References: <1431714237-880-6-git-send-email-toshi.kani@hp.com> <1432628901-18044-6-git-send-email-bp@alien8.de> <20150731131802.GW25159@twins.programming.kicks-ass.net> <20150731144452.GA8106@nazgul.tnic> <20150731150806.GX25159@twins.programming.kicks-ass.net> <20150731152713.GA9756@nazgul.tnic> <20150801142820.GU30479@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20150801142820.GU30479@wotan.suse.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 01, 2015 at 04:28:20PM +0200, Luis R. Rodriguez wrote: > I need to update this documentation to remove set_memory_wc() there as we've > learned with the MTRR --> PAT conversion that set_memory_wc() cannot be used on > IO memory, it can only be used for RAM. I am not sure if I would call it being > broken that you cannot use set_memory_*() for IO memory that may have been by > design. Well, it doesn't really make sense to write-combine IO memory, does it? My simplistic impression is that an IO range behind which there's a device, cannot stomach any caching of IO as all commands/data accesses need to happen as they get issued... -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f179.google.com (mail-wi0-f179.google.com [209.85.212.179]) by kanga.kvack.org (Postfix) with ESMTP id E2BFD6B0038 for ; Sat, 1 Aug 2015 12:33:14 -0400 (EDT) Received: by wibxm9 with SMTP id xm9so66108854wib.1 for ; Sat, 01 Aug 2015 09:33:14 -0700 (PDT) Received: from mail.skyhub.de (mail.skyhub.de. [2a01:4f8:120:8448::d00d]) by mx.google.com with ESMTP id cg18si15687602wjb.154.2015.08.01.09.33.12 for ; Sat, 01 Aug 2015 09:33:13 -0700 (PDT) Date: Sat, 1 Aug 2015 18:33:11 +0200 From: Borislav Petkov Subject: Re: [tip:x86/mm] x86/mm/mtrr: Clean up mtrr_type_lookup() Message-ID: <20150801163311.GA15356@nazgul.tnic> References: <1431714237-880-6-git-send-email-toshi.kani@hp.com> <1432628901-18044-6-git-send-email-bp@alien8.de> <20150731131802.GW25159@twins.programming.kicks-ass.net> <20150731144452.GA8106@nazgul.tnic> <20150731150806.GX25159@twins.programming.kicks-ass.net> <20150731152713.GA9756@nazgul.tnic> <20150801142820.GU30479@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20150801142820.GU30479@wotan.suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: "Luis R. Rodriguez" Cc: Toshi Kani , Peter Zijlstra , mingo@kernel.org, hpa@zytor.com, dvlasenk@redhat.com, bp@suse.de, akpm@linux-foundation.org, brgerst@gmail.com, tglx@linutronix.de, linux-mm@kvack.org, luto@amacapital.net, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org On Sat, Aug 01, 2015 at 04:28:20PM +0200, Luis R. Rodriguez wrote: > I need to update this documentation to remove set_memory_wc() there as we've > learned with the MTRR --> PAT conversion that set_memory_wc() cannot be used on > IO memory, it can only be used for RAM. I am not sure if I would call it being > broken that you cannot use set_memory_*() for IO memory that may have been by > design. Well, it doesn't really make sense to write-combine IO memory, does it? My simplistic impression is that an IO range behind which there's a device, cannot stomach any caching of IO as all commands/data accesses need to happen as they get issued... -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- 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