Re: [PATCH] ACPI: acenv: Permit compilation from within the kernel

On Mon, Nov 20, 2023 at 5:19 PM Dave Jiang [off-list ref] wrote:

On 11/20/23 08:46, Rafael J. Wysocki wrote:

quoted

On Tue, Nov 14, 2023 at 7:09 PM Sam Edwards [off-list ref] wrote:

quoted

On 11/13/23 16:08, Linus Walleij wrote:

quoted

After commit a103f46633fd the kernel stopped compiling for
several ARM32 platforms that I am building with a bare metal
compiler. Bare metal compilers (arm-none-eabi-) don't
define __linux__.

Hi Linus,

I saw the same baremetal-compiler error here on the ARM64 side of the
fence, and narrowed the problem to the same commit as you.

quoted

This is because the header <acpi/platform/acenv.h> is now
in the include path for <linux/irq.h>:

More generally, I think it's because of this addition to linux/acpi.h:
+#include <linux/fw_table.h>

linux/acpi.h is supposed to ensure _LINUX is defined (if it isn't
already done by a non-baremetal compiler) before we start pulling in
ACPICA includes, so that ACPICA knows the platform. But because
fw_table.h contains:
#include <linux/acpi.h>
#include <acpi/acpi.h>

...the circular include does nothing (linux/acpi.h's include guard stops
the include before _LINUX is defined) and we end up pulling in
acpi/acpi.h before we're ready.

Not including either causes compile errors for me.

Interesting.  What errors do you get if you include linux/acpi.h only?

It should not be necessary to include acpi/acpi.h in addition to
linux/acpi.h, because the latter is expected to include the former.
If it doesn't do that, something is amiss.

And directly including acpi/acpi.h w/o linux/acpi.h causes triggering the #error and some other stuff:

./include/acpi/platform/aclinux.h:18:2: error: #error "Please don't include <acpi/acpi.h> directly, include <linux/acpi.h> instead."
   18 | #error "Please don't include <acpi/acpi.h> directly, include <linux/acpi.h> instead."
      |  ^~~~~


Only including linux/acpi.h:
In file included from ./include/linux/acpi.h:18,
                 from init/main.c:30:
./include/linux/fw_table.h:32:37: error: field ‘common’ has incomplete type
   32 |         struct acpi_subtable_header common;
      |                                     ^~~~~~
./include/linux/fw_table.h:33:36: error: field ‘hmat’ has incomplete type
   33 |         struct acpi_hmat_structure hmat;
      |                                    ^~~~
./include/linux/fw_table.h:34:40: error: field ‘prmt’ has incomplete type
   34 |         struct acpi_prmt_module_header prmt;
      |                                        ^~~~
./include/linux/fw_table.h:35:33: error: field ‘cedt’ has incomplete type
   35 |         struct acpi_cedt_header cedt;
      |                                 ^~~~

quoted

Yes, that's the problem AFAICS.  Dave?

What about moving the fw_table.h include in linux/acpi.h below the
mutex.h one, along with the EXPORT_SYMBOL_ACPI_LIB-related
definitions?

This builds cleanly for me.

OK, so I'm wondering if this also helps the other people in this thread.

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