Messages in this thread | | | Date | Wed, 5 Dec 2018 05:54:06 -0800 | From | Christoph Hellwig <> | Subject | Re: [PATCH v4 3/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging |
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On Wed, Dec 05, 2018 at 01:48:28PM +0800, Nicolas Boichat wrote: > IOMMUs using ARMv7 short-descriptor format require page tables > (level 1 and 2) to be allocated within the first 4GB of RAM, even > on 64-bit systems.
> +#ifdef CONFIG_ZONE_DMA32 > +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32 > +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA32 > +#else > +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA > +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA > +#endif
How does using GFP_DMA make sense based on the above? If the system has more than 32-bits worth of RAM it should be using GFP_DMA32, else GFP_KERNEL, not GFP_DMA for an arch defined small addressability pool.
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