From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] x86: change IO-APIC ack method default for single IO-APIC systems Date: Wed, 21 Jan 2009 14:35:54 +0000 Message-ID: References: <49773D8A.76E4.0078.0@novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <49773D8A.76E4.0078.0@novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 21/01/2009 14:21, "Jan Beulich" wrote: > "ioapic_ack=old". With that knowledge I think it is now reasonable to > include that patch in -unstable, as the introduction of the 'new' ack > method was only to address issues with certain chipsets silently > setting up alternative IRQ routes when RTEs in secondary IO-APICs got > masked. I don't specifically recall that this issue required two IO-APICs. In fact I think it did not. It was actually something to do with the chipset trying to distinguish between an OS using 'legacy' routing versus 'mp-bios' routing, via a rather distasteful IO-APIC hack. Unfortunately the hack was not that uncommon and I don't think those chipsets had more than one IO-APIC. Overall I think ack_type new has worked quite well. I was actually about to remove the old ack_type! (But now I won't ;-) I'm not inclined to take this patch though. -- Keir