Re: [PATCH v4 3/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging

Christoph Hellwig
2018-12-05T14:43:14Z

On Wed, Dec 05, 2018 at 02:40:06PM +0000, Robin Murphy wrote:
> 32-bit Arm doesn't have ZONE_DMA32, but has (or at least had at the time) a
> 2GB ZONE_DMA. Whether we actually need that or not depends on how this all
> interacts with LPAE and highmem, but I'm not sure of those details off-hand.

Well, arm32 can't address more than 32-bits in the linear kernel
mapping, so GFP_KERNEL should be perfectly fine there if the limit
really is 32-bits and not 31 or smaller because someone stole a bit
or two somewhere.