# Re: \[PATCH RESEND v3\] ACPI: Add memory semantics to acpi\_os\_map\_memory()

- From: Catalin Marinas \<catalin.marinas@arm.com\>
- Date: 2021-08-23 12:31:04 
- List: linux-acpi
- Page: https://ratatoskr.run/linux-acpi/2021/08/1485793
- Thread: https://ratatoskr.run/linux-acpi/2021/07/1457305/t.md

```text
On Mon, Aug 23, 2021 at 11:46:18AM +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>
> ---
> Resending with all lists CC'ed.
> 
> Patch series is a v3 of a previous version[2]:
> 
> v2->v3:
> 	- Dropped first two-patches following LKML feedback[2]
> v1->v2
> 	- Added patch 1 and 2 according to feedback received on[1]
> 
> [1] https://lore.kernel.org/linux-acpi/20210726100026.12538-1-lorenzo.pieralisi@arm.com
> [2] https://lore.kernel.org/linux-acpi/20210802152359.12623-1-lorenzo.pieralisi@arm.com
> 
>  arch/arm64/include/asm/acpi.h |  3 +++
>  arch/arm64/kernel/acpi.c      | 19 ++++++++++++++++---
>  drivers/acpi/osl.c            | 23 ++++++++++++++++-------
>  include/acpi/acpi_io.h        |  8 ++++++++
>  4 files changed, 43 insertions(+), 10 deletions(-)

For arm64:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

I presume this patch would go in via the acpi tree.

-- 
Catalin
```