On Mon, Mar 18, 2013 at 12:14 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote: > Instead, try to explain why 5 is the correct value in the current code > and how it is (or should be!) derived. initial mapped size is PMD_SIZE, aka 2M. if we use step_size to be PUD_SIZE aka 1G, as most worse case that 1G is cross the 1G boundary, and PG_LEVEL_2M is not set, we will need 1+1+512 pages (aka 2M + 8k) to map 1G range with PTE. So i picked (30-21)/2 to get 5. Please check attached patch. Thanks Yinghai
Attachment:
add_comment_for_step_size.patch
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