Hi... On Wed, Oct 17, 2012 at 5:39 PM, Fan Yang <lljyangfan@gmail.com> wrote:
HI ALL: I don't knowe why the linux designer need to define the ZONE_HIGHEM, and why they defined it 896M.
my understanding about ZONE_HIGHMEM is that it is simply a pool of pages, grouped so you can quickly know that if you want to use them, you need to kmap() them first because they are normally beyond kernel addressable space 896? simple, because that is the upper border of kernel addressable space range. actually, it's 1 GiB, but since 128 MiB are reserved for various need: vmalloc, kmap mapping etc, then you get 1 GiB - 128 MiB--> there you go 128 MiB -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com