Re: [PATCH] xen: Add __GFP_DMA flag when xen_swiotlb_init gets free pages.

[David Vrabel <david.vrabel@citrix.com>]

On 20/04/15 11:48, Chen Baozi wrote:
> Make sure that xen_swiotlb_init allocates buffers that is DMA capable.
> 
> Signed-off-by: Chen Baozi <baozich@gmail.com>
> ---
>  drivers/xen/swiotlb-xen.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 810ad41..7345afd 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -235,7 +235,8 @@ retry:
>  #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
>  #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
>  		while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
> -			xen_io_tlb_start = (void *)__get_free_pages(__GFP_NOWARN, order);
> +			xen_io_tlb_start = (void *)__get_free_pages(
> +						__GFP_NOWARN|__GFP_DMA, order);

I think this breaks x86 where __GFP_DMA means below 16 MB.  Perhaps you
mean __GFP_DMA32?

David