Messages in this thread | | | Date | Fri, 18 Jan 2008 13:24:37 -0500 | From | Dave Jones <> | Subject | Re: [PATCH] X86: fix typo PAT to X86_PAT |
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On Fri, Jan 18, 2008 at 01:31:40PM +0100, Ingo Molnar wrote:
> * Yinghai Lu <Yinghai.Lu@Sun.COM> wrote: > > > > thanks. But, i think we should rather do the following: if X86_PAT > > > is eanbled then /proc/mtrr should be read-only. There's no problem > > > _looking_ at MTRR contents, as long as we do not try to modify them. > > > Hm? > > > > anyway > > > > depends on !PAT > > > > need to be removed. > > > > it seems when PAT is used, some code still touch MTRR. > > 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.
Dave
-- http://www.codemonkey.org.uk
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