linux-kernel - Re: [PATCH v2 3/3] ACPI: Add memory semantics to acpi_os_map

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Date:   Tue, 3 Aug 2021 10:16:05 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Catalin Marinas <catalin.marinas@....com>, rjw@...ysocki.net
Cc:     linux-kernel@...r.kernel.org, Hanjun Guo <guohanjun@...wei.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Will Deacon <will@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Veronika kabatova <vkabatov@...hat.com>,
        Robin Murphy <robin.murphy@....com>
Subject: Re: [PATCH v2 3/3] ACPI: Add memory semantics to acpi_os_map_memory()

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@...wei.com>
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> > Acked-by: Ard Biesheuvel <ardb@...nel.org>
> > Cc: Ard Biesheuvel <ardb@...nel.org>
> > Cc: Will Deacon <will@...nel.org>
> > Cc: Hanjun Guo <guohanjun@...wei.com>
> > Cc: Sudeep Holla <sudeep.holla@....com>
> > Cc: Catalin Marinas <catalin.marinas@....com>
> > Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> 
> For the arm64 bits:
> 
> Acked-by: Catalin Marinas <catalin.marinas@....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