From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: RE: iommu=0 leading to panic when system defaults to using x2apic Date: Tue, 14 Dec 2010 17:06:16 +0000 Message-ID: <4D07B2180200007800027E6B@vpn.id2.novell.com> References: <4D0215E0020000780002734A@vpn.id2.novell.com> <4D0224E602000078000273AD@vpn.id2.novell.com> <749B9D3DBF0F054390025D9EAFF47F22317AA2F4@shsmsx501.ccr.corp.intel.com> <4D0257D7020000780002747B@vpn.id2.novell.com> <987664A83D2D224EAE907B061CE93D530193BB9EB8@orsmsx505.amr.corp.intel.com> <4D07372F0200007800027BBF@vpn.id2.novell.com> <987664A83D2D224EAE907B061CE93D530193C384E4@orsmsx505.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <987664A83D2D224EAE907B061CE93D530193C384E4@orsmsx505.amr.corp.intel.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Allen M Kay , Yang Z Zhang Cc: Keir Fraser , "xen-devel@lists.xensource.com" , Weidong Han List-Id: xen-devel@lists.xenproject.org >>> On 14.12.10 at 17:53, "Kay, Allen M" wrote: >> And why is it that Xen panics when the BIOS pre-enabled x2apic >> mode without also enabling interrupt re-mapping, while Linux >> (afaict from looking at 2.6.32 code and output from an affected >> machine) simply enables interrupt re-mapping in this case? >=20 > AFAIK, Linux also requires interrupt remapping for x2apic. I believe=20 > Weidong has fixed the panic issue in Xen when x2apic is enabled = without=20 > enabling interrupt remapping. It should now behave the same way as = Linux. No - just look at the very first if() in enable_bsp_x2apic(). Jan