Messages in this thread | | | From | Jesse Barnes <> | Subject | Re: Intel's response Linux/MTRR/8GB Memory Support / Why doesn't the kernel realize the BIOS has problems and re-map appropriately? | Date | Fri, 1 Jun 2007 14:35:56 -0700 |
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On Friday, June 1, 2007 2:19:43 Andi Kleen wrote: > On Fri, Jun 01, 2007 at 02:07:51PM -0700, Jesse Barnes wrote: > > On Friday, June 1, 2007 2:14:17 Andi Kleen wrote: > > > Jesse Barnes <jbarnes@virtuousgeek.org> writes: > > > > (or we get proper PAT support, which I think would make this problem > > > > go away as well). > > > > > > No it won't. If the basic MTRRs for memory are wrong just having PAT > > > support in drivers (which already exist in a limited form already, just > > > for UC only) won't change anything. > > > > No obviously just using PAT for drivers wouldn't help, I was thinking > > more of having one PAT type be WB memory, and using it by default for > > most PTEs > > Then the BIOS couldn't override it anymore in case it is needed somewhere. > e.g. normally we just use normal 2MB direct mappings for the hole > if there is memory beyond it and the hole doesn't need to be 2MB aligned. > Just assuming UC for all reserved pages would be also pretty drastic > and likely result in many 2MB pages being split and using a lot more > TLB. > > > covering normal memory. If that's not possible, then it seems sensible > > to > > And normally the MTRRs win, don't they (if I remember the table correctly) > So if the MTRR says UC and PAT disagrees it might not actually help
I didn't check that part of the spec, that might be true. If so, then we really need some sort of MTRR fix no matter what.
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