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

From: lihuisong (C)
Date: Tue May 30 2023 - 07:37:47 EST

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.


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.
Thank you. will drop this patch.