Messages in this thread |  | | | Date | Fri, 18 Jan 2008 22:02:10 +0100 | | From | Ingo Molnar <> | | Subject | Re: [PATCH] X86: fix typo PAT to X86_PAT |
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* Dave Jones <davej@redhat.com> wrote:
> > you mean modifies MTRRs? Which code is that? (besides the > > /proc/mtrr userspace API) > > This exclusion is going to be a real pain in the ass for distro > kernels. It's impossible for example to build a kernel that will now > support the MTRR-alike registers on the AMD K6/early Cyrix etc and > also support PAT. > > Additionally, given people tend to update their kernels a lot more > often than they update to a whole new version of X, it means until > userspace has caught up, we can't ship a kernel with PAT supported, or > else X gets a lot slower due to the missing mtrr support.
there's no exclusion enforced right now, and if a CPU is PAT-incapable (or if the kernel is booted nopat) then the MTRR bits should be usable. But if we boot with PAT enabled, and Xorg gets /proc/mtrr wrong, we'll see nasty crashes. If it gets them right, it should all still work just fine. Is this ok? Then, in a year or two, distros can disable write support to /proc/mtrr. Hm?
Ingo
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