Wei Huang
2011-Mar-01 21:11 UTC
[Xen-devel] [PATCH] Check AMD SYSCFG DramModEn bit for MTRR configuration
This patch checks whether SYSCFG DramModEn bit is clear by BIOS. Some buggy BIOS might set this bit to 1, which causes unexpected behavior on AMD platforms. This patch also increase family check for AMD CPUs when setting fixed MTRR ranges. Signed-off-by: Wei Huang <wei.huang2@amd.com> PS: If OK, please apply it to both xen-4.1 and xen-4.0 trees. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Huang2, Wei
2011-Mar-02 00:52 UTC
RE: [Xen-devel] [PATCH] Check AMD SYSCFG DramModEn bit for MTRR configuration
This patch has some problem on SMP system. I am creating another one. Sorry... -Wei -----Original Message----- From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of Wei Huang Sent: Tuesday, March 01, 2011 3:12 PM To: ''xen-devel@lists.xensource.com'' Subject: [Xen-devel] [PATCH] Check AMD SYSCFG DramModEn bit for MTRR configuration This patch checks whether SYSCFG DramModEn bit is clear by BIOS. Some buggy BIOS might set this bit to 1, which causes unexpected behavior on AMD platforms. This patch also increase family check for AMD CPUs when setting fixed MTRR ranges. Signed-off-by: Wei Huang <wei.huang2@amd.com> PS: If OK, please apply it to both xen-4.1 and xen-4.0 trees. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2011-Mar-02 07:01 UTC
Re: [Xen-devel] [PATCH] Check AMD SYSCFG DramModEn bit for MTRR configuration
On 01/03/2011 21:11, "Wei Huang" <wei.huang2@amd.com> wrote:> This patch checks whether SYSCFG DramModEn bit is clear by BIOS. Some > buggy BIOS might set this bit to 1, which causes unexpected behavior on > AMD platforms. This patch also increase family check for AMD CPUs when > setting fixed MTRR ranges.How common are these buggy BIOSes? Can''t we just get users to update their BIOS? -- Keir> Signed-off-by: Wei Huang <wei.huang2@amd.com> > > > PS: If OK, please apply it to both xen-4.1 and xen-4.0 trees. > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Anish Patel
2011-Mar-02 15:20 UTC
Re: [Xen-devel] [PATCH] Check AMD SYSCFG DramModEn bit for MTRR configuration
Buggy BIOSes are more common than you think. especially from small shops, and some times they don''t tend to release BIOS updates for their platforms. On 03/02/11 02:01, Keir Fraser wrote:> On 01/03/2011 21:11, "Wei Huang"<wei.huang2@amd.com> wrote: > >> This patch checks whether SYSCFG DramModEn bit is clear by BIOS. Some >> buggy BIOS might set this bit to 1, which causes unexpected behavior on >> AMD platforms. This patch also increase family check for AMD CPUs when >> setting fixed MTRR ranges. > How common are these buggy BIOSes? Can''t we just get users to update their > BIOS? > > -- Keir > >> Signed-off-by: Wei Huang<wei.huang2@amd.com> >> >> >> PS: If OK, please apply it to both xen-4.1 and xen-4.0 trees. >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xensource.com >> http://lists.xensource.com/xen-devel > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Wei Huang
2011-Mar-02 17:25 UTC
Re: [Xen-devel] [PATCH] Check AMD SYSCFG DramModEn bit for MTRR configuration
It is indeed very rare. But such bug, whenever it happens, is very hard to spot. Linux kernel forces this bit to clear when read fixed MTRR. I think we should at least print out a warning message. -Wei On Wed, 2011-03-02 at 09:20 -0600, Anish Patel wrote:> Buggy BIOSes are more common than you think. especially from small > shops, and some times they don''t tend to release BIOS updates for their > platforms. > > > > On 03/02/11 02:01, Keir Fraser wrote: > > On 01/03/2011 21:11, "Wei Huang"<wei.huang2@amd.com> wrote: > > > >> This patch checks whether SYSCFG DramModEn bit is clear by BIOS. Some > >> buggy BIOS might set this bit to 1, which causes unexpected behavior on > >> AMD platforms. This patch also increase family check for AMD CPUs when > >> setting fixed MTRR ranges. > > How common are these buggy BIOSes? Can''t we just get users to update their > > BIOS? > > > > -- Keir > > > >> Signed-off-by: Wei Huang<wei.huang2@amd.com> > >> > >> > >> PS: If OK, please apply it to both xen-4.1 and xen-4.0 trees. > >> > >> _______________________________________________ > >> Xen-devel mailing list > >> Xen-devel@lists.xensource.com > >> http://lists.xensource.com/xen-devel > > > > > > _______________________________________________ > > Xen-devel mailing list > > Xen-devel@lists.xensource.com > > http://lists.xensource.com/xen-devel > > > >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel