Re: [discuss] Re: [1/3] Add 4GB DMA32 zone

[Andi Kleen <ak@suse.de>]

Hmm ok description is not very enlightening. 4 zones should indeed
still fit into 2 bits.

Kamezawa-san, can you please explain why exactly you did that change?

Thanks,
-Andi

On Tuesday 13 September 2005 12:15, Andrew Morton wrote:
> Andi Kleen <ak@suse.de> wrote:
> > Andrew do you still have the patch with
> >  the description? It must have been between 2.6.13mm1 and  2.6.13mm2.
>
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>
> Because 2.6.13-mm2  adds new zone DMA32, ZONES_SHIFT becomes 3.
> So, flags bits reserved for (SECTION | NODE | ZONE) should be increase.
>
> ZONE_SHIFT is increased, FLAGS_RESERVED should be.
>
> Signed-off-by Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Andi Kleen <ak@muc.de>
> Signed-off-by: Andrew Morton <akpm@osdl.org>
> ---
>
>  include/linux/mmzone.h |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff -puN include/linux/mmzone.h~x86_64-dma32-fix include/linux/mmzone.h
> --- 25/include/linux/mmzone.h~x86_64-dma32-fix	Fri Sep  9 17:13:41 2005
> +++ 25-akpm/include/linux/mmzone.h	Fri Sep  9 17:14:13 2005
> @@ -431,9 +431,10 @@ extern struct pglist_data contig_page_da
>  #if BITS_PER_LONG == 32 || defined(ARCH_HAS_ATOMIC_UNSIGNED)
>  /*
>   * with 32 bit page->flags field, we reserve 8 bits for node/zone info.
> - * there are 3 zones (2 bits) and this leaves 8-2=6 bits for nodes.
> + * there are 4 zones (3 bits) and this leaves 8-2=6 bits for nodes.
> + * +6bits for sections if CONFIG_SPARSEMEM
>   */
> -#define FLAGS_RESERVED		8
> +#define FLAGS_RESERVED		9
>
>  #elif BITS_PER_LONG == 64
>  /*
> _