Messages in this thread | | | Date | Thu, 18 Aug 2016 05:12:54 -0600 | From | "Jan Beulich" <> | Subject | Re: [Xen-devel] XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC |
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>>> On 18.08.16 at 12:16, <andrew.cooper3@citrix.com> wrote: > On 18/08/16 11:06, Jan Beulich wrote: >>>>> On 17.08.16 at 22:32, <konrad.wilk@oracle.com> wrote: >>> Looking at the kernel it assumes that WB is ok for 640KB->1MB. >>> The comment says: >>> " /* Low ISA region is always mapped WB in page table. No need to track > *" >> As per above it's not clear to me what this comment is backed by. > > This states what is in the pagetables. Not the combined result with MTRRs. > > WB in the pagetables and WC/UB in the MTRRs is a legal combination which > functions correctly.
True, but then again - haven't I been told multiple times that Linux nowadays prefers to run without using MTRRs?
Jan
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