Messages in this thread | | | Date | Mon, 2 Apr 2007 10:34:38 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [PATCH 1/4] x86_64: Switch to SPARSE_VIRTUAL |
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On Mon, 2 Apr 2007, Andi Kleen wrote:
> > No no no. For the gazillions time: All of 1-1 mapped kernel memory on > > x86_64 needs a 2 MB page table entry. The virtual memmap uses the same. > > There are *no* additional TLBs used. > > But why do you reserve an own virtual area then if you claim to not use any > additional mappings?
The 1-1 area using mappings for 2MB pages right? So it uses a virtual 1-1 area. It already has a virtual mapping.
What we do for virtual memmap here is also use 2MB pages but order the pages a bit different so that they provide a linear memory map.
So the number of TLBs in use stays the same. There are a few additional higher level page table pages that are needed to provide the alternate view that generates the linear mapping but that is just a couple of pages.
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