Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756887AbYCTPJT (ORCPT ); Thu, 20 Mar 2008 11:09:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756124AbYCTPJI (ORCPT ); Thu, 20 Mar 2008 11:09:08 -0400 Received: from mx1.redhat.com ([66.187.233.31]:41975 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755835AbYCTPJI (ORCPT ); Thu, 20 Mar 2008 11:09:08 -0400 Message-ID: <47E27D08.9050809@redhat.com> Date: Thu, 20 Mar 2008 12:04:40 -0300 From: Glauber Costa User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: "Maciej W. Rozycki" CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu, ak@suse.de Subject: Re: [PATCH 45/79] [PATCH] fix apic acking of irqs References: <12059475744092-git-send-email-gcosta@redhat.com> <12059476883852-git-send-email-gcosta@redhat.com> <12059476932397-git-send-email-gcosta@redhat.com> <12059476971309-git-send-email-gcosta@redhat.com> <1205947702588-git-send-email-gcosta@redhat.com> <12059477063046-git-send-email-gcosta@redhat.com> <12059477102394-git-send-email-gcosta@redhat.com> <12059477143205-git-send-email-gcosta@redhat.com> <1205947719906-git-send-email-gcosta@redhat.com> <12059477234148-git-send-email-gcosta@redhat.com> <12059477273855-git-send-email-gcosta@redhat.com> <1205947732309-git-send-email-gcosta@redhat.com> <12059477371787-git-send-email-gcosta@redhat.com> <12059477421707-git-send-email-gcosta@redhat.com> <12059477472416-git-send-email-gcosta@redhat.com> <12059477521176-git-send! -email-gcosta@redhat.com> <12059477561937-git-send-email-gcosta@redhat <12059477792893-git-send-email-gcosta@redhat.com> In-Reply-To: Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1174 Lines: 24 Maciej W. Rozycki wrote: > On Wed, 19 Mar 2008, Glauber de Oliveira Costa wrote: > >> EOI is a write-only register. Using write around will have the effect >> of reading it, which will make all subsequent reads of the ESR register >> to return an error code. It was unnotices for quite a while because main sources >> of reading the ESR register where done prior to apic interrupt enabling. > > Are you sure this actually triggers for APIC chips affected by the > erratum in question? And please note that for them the effect of two > consecutive writes will be much more disastrous than setting a bit in the > ESR register. > > Maciej I'm not _sure_, but I can't find anything in the errata list that states otherwise. It would be great that anyone has such a system to test it. But with the current conditions, it will break bootup code. In case it is really a problem, we'd need to make a special case for that. -- 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/