Re: [PATCH] arm64: acpi: Export symbol for acpi_os_ioremap

[lihuisong (C)]

在 2023/5/30 18:58, Sudeep Holla 写道:
> On Mon, May 29, 2023 at 03:31:12PM +0200, Ard Biesheuvel wrote:
> > On Fri, 26 May 2023 at 15:12, lihuisong (C) <lihuisong@xxxxxxxxxx> wrote:
> > > 在 2023/5/26 20:39, Ard Biesheuvel 写道:
> > > > (cc Lorenzo)
> > > >
> > > > On Fri, 26 May 2023 at 14:20, Huisong Li <lihuisong@xxxxxxxxxx> wrote:
> > > > > The driver who calls the acpi_os_ioremap() cannot be compiled if the 'M'
> > > > > is selected for the driver. The compiling log is as follows:
> > > > > -->
> > > > > MODPOST Module.symvers
> > > > > ERROR: modpost: "acpi_os_ioremap" [drivers/soc/hisilicon/xxx.ko] undefined!
> > > > > scripts/Makefile.modpost:136: recipe for target 'Module.symvers' failed
> > > > > make[1]: *** [Module.symvers] Error 1
> > > > >
> > > > > So this patch exports symbol for acpi_os_ioremap.
> > > > That driver does not exist in mainline.
> > > We have an uploading driver [1] that may use it.
> > >
> > > [1]
> > > https://patchwork.kernel.org/project/linux-soc/patch/20230522072211.8894-2-lihuisong@xxxxxxxxxx/
> > >
> > > > Why does it need to use acpi_os_ioremap() instead of the ordinary
> > > > memremap/ioremap routines?
> > > This driver needs to ioremap the shared memory space of a PCC subspace.
> > > And @Sudeep suggested that we use this interface.
> > > It is suitable here.
> > I disagree. acpi_io_ioremap() is internal arch plumbing for the ACPI
> > subsystem. I don't see why we should use it here.
> Yes. One reason I suggested this was in past firmware authors had mixed
> the memory allocated for PCC and using acpi_io_ioremap() made sense. But
> I hear you and it make sense to avoid it especially if the driver must
> know what type of memory it is and must be dealing with.
>
> > On arm64, acpi_os_ioremap() cross references the EFI memory map to
> > figure out whether a physical region is memory or device, but a driver
> > should already know that.
> Agreed.
Thank you. will drop this patch.
>