Subject: Re: [PATCH] powerpc: Introduce address space "slices"

From: [email-masked] (Olof Johansson)
Date: Mon, 19 Feb 2007 09:33:15 -0600

On Mon, Feb 19, 2007 at 05:43:38PM +1100, Benjamin Herrenschmidt wrote:
> powerpc: Introduce address space "slices"
> 
> This patch provide some infrastructure that will allow proper creation
> of special VMAs with different page sizes on powerpc.
> 
> The basic issue is to be able to do what hugetlbfs does but with
> different page sizes for some other special filesystems, more
> specifically, my need is:
> 
>  - hugetlbfs should still work of course :-)
> 
>  - SPE local store mappings using 64K pages on a 4K base page size
> kernel on Cell

Why? What is the reason they can't use 4K pages?

>  - Some special 4K segments in 64K pages kernels for mapping a dodgy
> specie of powerpc specific infiniband hardware that requires 4K MMU
> mappings for various reasons I won't explain here.

-Olof