early_res and find_e820_area for i386?

["Huang, Ying" <ying.huang@intel.com>]

Hi,

Before bootmem allocator is available, kernel needs allocate memory
pages such as page table and some NUMA structures. On x86_64, this is
done by early_res and find_e820_area. On i386, this is done through
using the memory area after kernel itself which is tracked with
init_pg_tables_end.

Is it better to implement early_res and find_e820_area on i386? Can we
trust E820 table on i386?

Or we add an early_alloc, which allocate memory from the memory area
after kernel itself and check the early_res areas and E820 table too.

BTW: Why not merge e820_32.c and e820_64.c? At least part of them.

Best Regards,
Huang Ying