Messages in this thread | | | Subject | Re: [RFC PATCH 3/11] x86, mm, pat: Change reserve_memtype() to handle WT type | From | Toshi Kani <> | Date | Tue, 15 Jul 2014 17:10:01 -0600 |
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On Tue, 2014-07-15 at 12:56 -0700, Andy Lutomirski wrote: > On Tue, Jul 15, 2014 at 12:34 PM, Toshi Kani <toshi.kani@hp.com> wrote: > > This patch changes reserve_memtype() to handle the new WT type. > > When (!pat_enabled && new_type), it continues to set either WB > > or UC- to *new_type. When pat_enabled, it can reserve a given > > non-RAM range for WT. At this point, it may not reserve a RAM > > range for WT since reserve_ram_pages_type() uses the page flags > > limited to three memory types, WB, WC and UC. > > FWIW, last time I looked at this, it seemed like all the fancy > reserve_ram_pages stuff was unnecessary: shouldn't the RAM type be > easy to track in the direct map page tables?
Are you referring the direct map page tables as the kernel page directory tables (pgd/pud/..)?
I think it needs to be able to keep track of the memory type per a physical memory range, not per a translation, in order to prevent aliasing of the memory type.
Thanks, -Toshi
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