Re: [PATCH 1/5] mm: add coherence API for DMA to vmalloc/vmap areas

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Wed, 2009-09-09 at 03:17 +0000, James Bottomley wrote:
> On Virtually Indexed architectures (which don't do automatic alias
> resolution in their caches), we have to flush via the correct
> virtual address to prepare pages for DMA.  On some architectures
> (like arm) we cannot prevent the CPU from doing data movein along
> the alias (and thus giving stale read data), so we not only have to
> introduce a flush API to push dirty cache lines out, but also an invalidate
> API to kill inconsistent cache lines that may have moved in before
> DMA changed the data
> 
> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
> ---
>  include/linux/highmem.h |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index 211ff44..9719952 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -17,6 +17,12 @@ static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page
>  static inline void flush_kernel_dcache_page(struct page *page)
>  {
>  }
> +static incline void flush_kernel_dcache_addr(void *vaddr)
> +{
> +}
> +static incline void invalidate_kernel_dcache_addr(void *vaddr)
> +{
> +}
>  #endif

OK, so it's been pointed out to me that I didn't compile check this ...
just testing to see everyone is awake ...

James