Re: [PATCH 2/6] Introduce CONFIG_ZONE_DMA

Christoph Lameter
2006-09-18T17:30:58Z

On Mon, 18 Sep 2006, James Bottomley wrote:

> 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).

What does parisc do with GENERIC_ISA_DMA? I see

config GENERIC_ISA_DMA
bool

No default and no explanation?

Can I drop this from parisc's Kconfig? Is GENERIC_ISA_DMA set or not?