Hello,
On Wed, Sep 25, 2013 at 02:30:51AM +0800, Zhang Yanfei wrote:
> +/**
> + * memory_map_bottom_up - Map [map_start, map_end) bottom up
> + * @map_start: start address of the target memory range
> + * @map_end: end address of the target memory range
> + *
> + * This function will setup direct mapping for memory range
> + * [map_start, map_end) in bottom-up.
Ditto about the comment.
> + */
> +static void __init memory_map_bottom_up(unsigned long map_start,
> + unsigned long map_end)
> +{
> + unsigned long next, new_mapped_ram_size, start;
> + unsigned long mapped_ram_size = 0;
> + /* step_size need to be small so pgt_buf from BRK could cover it */
> + unsigned long step_size = PMD_SIZE;
> +
> + start = map_start;
> + min_pfn_mapped = start >> PAGE_SHIFT;
> +
> + /*
> + * We start from the bottom (@map_start) and go to the top (@map_end).
> + * The memblock_find_in_range() gets us a block of RAM from the
> + * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
> + * for page table.
> + */
> + while (start < map_end) {
> + if (map_end - start > step_size) {
> + next = round_up(start + 1, step_size);
> + if (next > map_end)
> + next = map_end;
> + } else
> + next = map_end;
> +
> + new_mapped_ram_size = init_range_memory_mapping(start, next);
> + start = next;
> +
> + if (new_mapped_ram_size > mapped_ram_size)
> + step_size <<= STEP_SIZE_SHIFT;
> + mapped_ram_size += new_mapped_ram_size;
> + }
> +}
As Yinghai pointed out in another thread, do we need to worry about
falling back to top-down?
Thanks.
--
tejun
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