From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suravee Suthikulpanit Subject: Re: [PATCH 3/3] x86/AMD-Vi: Fix IVRS HPET special->handle override Date: Wed, 25 Sep 2013 10:01:12 -0500 Message-ID: <5242FAB8.2090501@amd.com> References: <1379115031-1992-1-git-send-email-suravee.suthikulpanit@amd.com> <1379115031-1992-4-git-send-email-suravee.suthikulpanit@amd.com> <5236D75E02000078000F3847@nat28.tlf.novell.com> <523862B8.8000207@amd.com> <523891C902000078000F4070@nat28.tlf.novell.com> <523CC05C.7030903@amd.com> <5240014202000078000F555E@nat28.tlf.novell.com> <524070E8.8000900@amd.com> <524151B002000078000F5C58@nat28.tlf.novell.com> <52421F97.6080902@amd.com> <52429AF002000078000F6103@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VOqbm-0007ZG-Kc for xen-devel@lists.xenproject.org; Wed, 25 Sep 2013 15:02:30 +0000 In-Reply-To: <52429AF002000078000F6103@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel List-Id: xen-devel@lists.xenproject.org On 9/25/2013 1:12 AM, Jan Beulich wrote: >>>> On 25.09.13 at 01:26, Suravee Suthikulanit wrote: >> Ok, after looking into Intel HPET specification, I can see that the spec >> allows a particular system >> to have multiple HPETs. And Jan was correct that only one is required >> to be listed in the APCI HPET table. >> The rest are listed in ACPI namespace. >> >> I look at the "arch/x86/hpet.c" and saw that this supports discovery in >> the ACPI HPET table. >> However, there is only one "hpet_address" and "hpet_blockid", which are >> initialized in the >> "arch/x86/acpi/boot.c: acpi_parse_hpet()". If the code were to support >> more than one HPET, >> this would have to be changed also. Do you expect these to change as well? > This second paragraph contradicts what you correctly describe in > the first: There's only one required to be listed in the ACPI HPET > table, and hence that code isn't expected to change. > >> Also, I don't see the code that would walk the ACPI namespace anywhere. >> Does it exist? > In Dom0, yes. But the information not getting passed down is of > no relevance here: All we care about is how to correctly find the > IOMMU for the one HPET we use, which ought to work no matter > how many HPETs there are in the system. > > Jan Actually, I found out that "struct hpet_sbdf.iommu" is not used anywhere. We should be able to get rid of this, and it should now be simpler logic. I'll remove this in my next patch. Suravee