Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752308AbZFJEYo (ORCPT ); Wed, 10 Jun 2009 00:24:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750856AbZFJEYh (ORCPT ); Wed, 10 Jun 2009 00:24:37 -0400 Received: from terminus.zytor.com ([198.137.202.10]:42946 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750808AbZFJEYg (ORCPT ); Wed, 10 Jun 2009 00:24:36 -0400 Message-ID: <4A2F353A.9040007@kernel.org> Date: Tue, 09 Jun 2009 21:23:22 -0700 From: "H. Peter Anvin" Organization: Linux Kernel Organization, Inc. User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Ingo Molnar CC: Harald Welte , Jaswinder Singh Rajput , linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [PATCH] X86: cpu_debug support for VIA / Centaur CPU's References: <20090609082931.GD25316@prithivi.gnumonks.org> <1244537598.2558.9.camel@ht.satnam> <20090609145305.GD3986@prithivi.gnumonks.org> <20090609151557.GA9362@elte.hu> In-Reply-To: <20090609151557.GA9362@elte.hu> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 763 Lines: 25 Ingo Molnar wrote: > > MSRs should really be enumerated along CPU features. They will be > accessed if a CPU offers that CPU feature. > Nice in theory, but so many MSRs have to be enumerated with obscure test combinations, that it really isn't practical in the general case. That is why we have the safe MSR variants. > > Yeah, the safe read should never fault - there should be all zeroes > or an error return. > Error return, MSRs #GP if not present. All zero means a present MSR (which is zero.) -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/