Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752406AbdF3TJT (ORCPT ); Fri, 30 Jun 2017 15:09:19 -0400 Received: from mail.rc.ru ([151.236.222.147]:50730 "EHLO mail.rc.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751810AbdF3TJS (ORCPT ); Fri, 30 Jun 2017 15:09:18 -0400 X-Greylist: delayed 2252 seconds by postgrey-1.27 at vger.kernel.org; Fri, 30 Jun 2017 15:09:17 EDT Date: Fri, 30 Jun 2017 19:30:57 +0100 From: Ivan Kokshaysky To: Linus Torvalds Cc: Thomas Gleixner , Andi Kleen , Yinghai Lu , Stephane Eranian , "H. Peter Anvin" , Ingo Molnar , Peter Zijlstra , Borislav Petkov , Linux Kernel Mailing List , Bjorn Helgaas , Matthew Wilcox , "linux-tip-commits@vger.kernel.org" Subject: Re: [tip:x86/platform] x86/PCI/mmcfg: Switch to ECAM config mode if possible Message-ID: <20170630183057.GA27351@mail.rc.ru> References: <20170316215057.452220163@linutronix.de> <20170630031849.GP23705@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Content-Length: 997 Lines: 26 On Fri, Jun 30, 2017 at 10:16:15AM -0700, Linus Torvalds wrote: > On Fri, Jun 30, 2017 at 7:30 AM, Thomas Gleixner wrote: > >> But MCFG problems were a long time ago and noone uses these systems anymore, > >> so perhaps he is right. > > > > The obvious solution to this is to force type 1 for older machines, i.e. <= > > K8. Some day we should stop supporting 15+ years old crap just because we > > can. > > No. > > The fact is, type 1 is the *good* thing. It's the standard thing that > has worked pretty much forever, and that is not just tested, but has > good semantics. Fully agreed. Also, config space accesses supposed to be *safe* rather than *fast*. There was quite a heated discussion on this very subject back in 2008. Thought that I have a full copy of that, but no, surprisingly... Google still gives a sufficient part of that: http://linux-kernel.2935.n7.nabble.com/Patch-v2-Make-PCI-extended-config-space-MMCONFIG-a-driver-opt-in-td243861i60.html Ivan.