# Re: \[PATCH v2 3/3\] ACPI: Add memory semantics to acpi\_os\_map\_memory()

- From: Lorenzo Pieralisi \<hidden\>
- Date: 2021-08-03 09:16:18 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2021/08/1466252
- Thread: https://ratatoskr.run/linux-acpi/2021/07/1457305/t.md

```text
On Mon, Aug 02, 2021 at 05:46:22PM +0100, Catalin Marinas wrote:
> On Mon, Aug 02, 2021 at 04:23:59PM +0100, Lorenzo Pieralisi wrote:
> > The memory attributes attached to memory regions depend on architecture
> > specific mappings.
> > 
> > For some memory regions, the attributes specified by firmware (eg
> > uncached) are not sufficient to determine how a memory region should be
> > mapped by an OS (for instance a region that is define as uncached in
> > firmware can be mapped as Normal or Device memory on arm64) and
> > therefore the OS must be given control on how to map the region to match
> > the expected mapping behaviour (eg if a mapping is requested with memory
> > semantics, it must allow unaligned accesses).
> > 
> > Rework acpi_os_map_memory() and acpi_os_ioremap() back-end to split
> > them into two separate code paths:
> > 
> > acpi_os_memmap() -> memory semantics
> > acpi_os_ioremap() -> MMIO semantics
> > 
> > The split allows the architectural implementation back-ends to detect
> > the default memory attributes required by the mapping in question
> > (ie the mapping API defines the semantics memory vs MMIO) and map the
> > memory accordingly.
> > 
> > Link: https://lore.kernel.org/linux-arm-kernel/31ffe8fc-f5ee-2858-26c5-0fd8bdd68702@arm.com
> > Tested-by: Hanjun Guo <guohanjun@huawei.com>
> > Signed-off-by: Lorenzo Pieralisi <redacted>
> > Acked-by: Ard Biesheuvel <ardb@kernel.org>
> > Cc: Ard Biesheuvel <ardb@kernel.org>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Hanjun Guo <guohanjun@huawei.com>
> > Cc: Sudeep Holla <redacted>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: "Rafael J. Wysocki" <redacted>
> 
> For the arm64 bits:
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> 
> I presume this will get merged via the ACPI tree?

Thank you, I don't know what's the best option in Rafael's opinion
(of course if he is OK with the patches which are mostly touching
ACPI code).

Lorenzo

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