As described in http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6650717 3.2 and later have tightened checks such that Solaris is now broken. Joe''s comment (which you can''t see for some reason) says: "Strictly speaking we''re not changing Xen''s heap mappings. The issue is that we are creating new mappings to Xen heap pages that have not full caching attributes. Intel says that all mappings to a given page should use the same caching attributes. It appears that Xen is now enforcing that with a check." This is a fairly nasty compatibility issue, but then, Solaris is "wrong" in trying to add the mappings as they are. Is there a sensible way to fix this breakage in Xen? regards john _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 11/3/08 18:05, "John Levon" <levon@movementarian.org> wrote:> "Strictly speaking we''re not changing Xen''s heap mappings. The issue > is that we are creating new mappings to Xen heap pages that have > not full caching attributes. Intel says that all mappings to a given > page should use the same caching attributes. It appears that Xen > is now enforcing that with a check." > > This is a fairly nasty compatibility issue, but then, Solaris is "wrong" > in trying to add the mappings as they are. Is there a sensible way to > fix this breakage in Xen?Xen could silently re-set the PAT flags in the PTE, rather than fail the PTE update completely. I''m fearful that just stores up trouble for future though, by reducing bug visibility. Also the guest may not like having its PTEs mangled in this way. And, since this is a workaround for old guests, we''d have to make this distasteful behaviour the default! -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Tue, Mar 11, 2008 at 06:21:36PM +0000, Keir Fraser wrote:> > "Strictly speaking we''re not changing Xen''s heap mappings. The issue > > is that we are creating new mappings to Xen heap pages that have > > not full caching attributes. Intel says that all mappings to a given > > page should use the same caching attributes. It appears that Xen > > is now enforcing that with a check." > > > > This is a fairly nasty compatibility issue, but then, Solaris is "wrong" > > in trying to add the mappings as they are. Is there a sensible way to > > fix this breakage in Xen? > > Xen could silently re-set the PAT flags in the PTE, rather than fail the PTE > update completely. I''m fearful that just stores up trouble for future > though, by reducing bug visibility. Also the guest may not like having its > PTEs mangled in this way. And, since this is a workaround for old guests, > we''d have to make this distasteful behaviour the default!It looks like we''re just going to eat the incompatibility on this one. regards john _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel