[PATCH] ARM: mm: Fix ARCH_LOW_ADDRESS_LIMIT when CONFIG_ZONE_DMA

[Russell King (Oracle)]

On Sat, Jun 03, 2023 at 02:33:49PM +0200, Arnd Bergmann wrote:
> Changing the low address limit by itself makes the swiotlb work
> correctly, but for performance we also want to avoid having to
> use the swiotlb at all when dealing with the zero page.

How often is the zero page used for DMA _to_ a device (it should never
be used for DMA _from_ a device.) ? It doesn't sound that useful to me,
since it can only be used for writing zeros.

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