Re: [PATCH 2/6] Introduce CONFIG_ZONE_DMA

James Bottomley
2006-09-18T14:58:05Z

On Mon, 2006-09-18 at 14:55 +0100, Christoph Hellwig wrote:
> Let's pass this on to linux-arch so that the arch maintainers can give input
> whether they need ZONE_DMA or not. If this just sneaks in unseen I'd bet
> various architectures will just keept it around despite not needing it.

Right at the moment, parisc has no use for ZONE_DMA. We basically set
ZONE_DMA = ZONE_NORMAL. I don't believe our 32 bit systems will ever
need it. On the 64 bit systems currently we insist on having an IOMMU
for every transaction, so ZONE_DMA = ZONE_NORMAL still. However, on
the zx1 systems, I can see us eventually implementing IOMMU bypass and
for that case, we might need ZONE_DMA (primarily for GFP_DMA32, I
suppose, which we could do internally).

James