Re: [PATCH v4 0/6] Cache coherency management subsystem

Conor Dooley
2025-10-22T20:47:31Z

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On Wed, Oct 22, 2025 at 12:22:41PM -0700, Andrew Morton wrote:
> On Wed, 22 Oct 2025 12:33:43 +0100 Jonathan Cameron <Jonathan.Cameron@huawei.com> wrote:
>
> > Support system level interfaces for cache maintenance as found on some
> > ARM64 systems. This is needed for correct functionality during various
> > forms of memory hotplug (e.g. CXL). Typical hardware has MMIO interface
> > found via ACPI DSDT.
> >
> > Includes parameter changes to cpu_cache_invalidate_memregion() but no
> > functional changes for architectures that already support this call.
>
> I see additions to lib/ so presumably there is an expectation that
> other architectures might use this.
>
> Please expand on this. Any particular architectures in mind? Any
> words of wisdom which maintainers of those architectures might benefit
> from?

It seems fairly probable that we're gonna end up with riscv systems
where drivers are being used for both this and the existing non-standard
cache ops stuff.

> > How to merge? When this is ready to proceed (so subject to review
> > feedback on this version), I'm not sure what the best route into the
> > kernel is. Conor could take the lot via his tree for drivers/cache but
> > the generic changes perhaps suggest it might be better if Andrew
> > handles this? Any merge conflicts in drivers/cache will be trivial
> > build file stuff. Or maybe even take it throug one of the affected
> > trees such as CXL.
>
> Let's not split the series up. Either CXL or COnor's tree is fine my
> me.

CXL is fine by me, greater volume there probably by orders of magnitude.

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