Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752406AbdF3TJT (ORCPT <rfc822;w@1wt.eu>);
        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 <rfc822;linux-kernel@vger.kernel.org>);
        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 <ink@jurassic.park.msu.ru>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <ak@linux.intel.com>,
        Yinghai Lu <yinghai@kernel.org>, Stephane Eranian <eranian@google.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Matthew Wilcox <willy@linux.intel.com>,
        "linux-tip-commits@vger.kernel.org" 
        <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>
 <tip-b5b0f00c760b6e9673ab79b88ede2f3c7a039f74@git.kernel.org>
 <CAE9FiQVAqZRtMLKTtySaCiCbDicN0h=6dPXEGP1M2eAq9AiYXQ@mail.gmail.com>
 <20170630031849.GP23705@tassilo.jf.intel.com>
 <alpine.DEB.2.20.1706301623040.1748@nanos>
 <CA+55aFwi0tkdugfqNEz6M28RXM2jx6WpaDF4nfA=doUVdZgUNQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CA+55aFwi0tkdugfqNEz6M28RXM2jx6WpaDF4nfA=doUVdZgUNQ@mail.gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
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 <tglx@linutronix.de> 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.