[PATCH] arm64: cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES)

[Arnd Bergmann]

On Thu, May 27, 2021 at 3:19 PM Mark Rutland <mark.rutland at arm.com> wrote:
> > More recently, it has been reported that a ARCH_DMA_MINALIGN of 128
> > bytes wastes considerable memory (~6% immediately after boot on one
> > system).
> >
> > Reduce ARCH_DMA_MINALIGN to 64 bytes and allow the warning/taint to
> > indicate if there are machines that unknowingly rely on this.
>
> The rationale above makes sense to me, so:
>
> Acked-by: Mark Rutland <mark.rutland at arm.com>

I think it would make sense to go even further than this in the
future, and allow
setting a smaller minimum alignment depending what hardware is detected
at boot time. That would clearly require more work and testing to do right,
so for the moment, this approach is the best we can do.

Acked-by: Arnd Bergmann <arnd at arndb.de>