• Yinghai Lu's avatar
    x86, mm: setup page table in top-down · 8d57470d
    Yinghai Lu authored
    Get pgt_buf early from BRK, and use it to map PMD_SIZE from top at first.
    Then use mapped pages to map more ranges below, and keep looping until
    all pages get mapped.
    
    alloc_low_page will use page from BRK at first, after that buffer is used
    up, will use memblock to find and reserve pages for page table usage.
    
    Introduce min_pfn_mapped to make sure find new pages from mapped ranges,
    that will be updated when lower pages get mapped.
    
    Also add step_size to make sure that don't try to map too big range with
    limited mapped pages initially, and increase the step_size when we have
    more mapped pages on hand.
    
    We don't need to call pagetable_reserve anymore, reserve work is done
    in alloc_low_page() directly.
    
    At last we can get rid of calculation and find early pgt related code.
    
    -v2: update to after fix_xen change,
         also use MACRO for initial pgt_buf size and add comments with it.
    -v3: skip big reserved range in memblock.reserved near end.
    -v4: don't need fix_xen change now.
    -v5: add changelog about moving about reserving pagetable to alloc_low_page.
    Suggested-by: default avatar"H. Peter Anvin" <hpa@zytor.com>
    Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
    Link: http://lkml.kernel.org/r/1353123563-3103-22-git-send-email-yinghai@kernel.orgSigned-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
    8d57470d
pgtable.h 18.7 KB