thanks make sense. thanks
On 10/16/07, Matthew Dillon <[EMAIL PROTECTED]> wrote: > > : > :just for curious: what is recursive pml4 mapping, found from freebsd pmap.h > : > :also, freebsd only have a page of PML4 entries, about 4K/64=64 > :entries, not all 512 (2**9). > > I'm not sure but I think what they are doing is mapping the page table > itself with a page table entry. > > For example, under i386 if you take the page directory address and > program that into one of the page directory array slots, what you > get at that address is a representation of the page table. > > [pde] -> [page_table0] -------> [normal-page-in-memory0] > [page_table1] [normal-page-in-memory1] > [page_table2] [normal-page-in-memory2] > [page_table3] > [page_table4] > [pde] -----------> [page_table-page-in-memory0] > [page_table6] [page_table-page-in-memory1] > ... [page_table-page-in-memory2] > ... > > This allows the system to look up a page table entry directly in > memory by indexing relative to some base address. > > I do not think we need to map page tables into memory because we > will have a direct physical map available and can do the translations > manually without having to load down the TLB more then it is already. > > -Matt > >
