Build regression since v6.6-rc1

Dear all,

since v6.6-rc1 (actually introduced with [1], specific commit on [2])
the kernel build for ia64 fails like that:

```
Making kernel...
time make -j24
LOCALVERSION="-0bb80ecc33a8fb5a682236443c1e740d5c917d1d-ia64" ARCH=ia64
CROSS_COMPILE=ia64-linux- all
Mon Sep 11 06:24:43 PM CEST 2023
[...]
   LD [M]  net/sunrpc/sunrpc.ko
ia64-linux-ld: drivers/acpi/acpi_processor.o: in function
`acpi_early_processor_osc':
/usr/src/linux-on-ramdisk/torvalds-linux/drivers/acpi/acpi_processor.c:596:
undefined reference to `acpi_proc_quirk_mwait_check'
ia64-linux-ld: drivers/acpi/processor_pdc.o: in function
`acpi_early_processor_set_pdc':
/usr/src/linux-on-ramdisk/torvalds-linux/drivers/acpi/processor_pdc.c:113:
undefined reference to `acpi_proc_quirk_mwait_check'
make[2]: *** [scripts/Makefile.vmlinux:36: vmlinux] Error 1
make[1]: *** [/usr/src/linux-on-ramdisk/torvalds-linux/Makefile:1165:
vmlinux] Error 2
make: *** [Makefile:234: __sub-make] Error 2

real    3m25.286s
user    69m26.895s
sys    6m37.619s
2
```

[1]:
https://github.com/torvalds/linux/commit/9bd0c413b90c6517b4a2fbedb74f50df3421b50c

[2]: https://github.com/torvalds/linux/commit/0a0e2ea642f6

In short, the change introduced a function call ([3]) in effect for ia64
without providing an implementation for that function for ia64. There's
a discussion thread on [4] that also includes a patch ([5]) to "fix" the
problem but that one unfortunately wasn't included in [1] or [2]:

```
---
  drivers/acpi/internal.h |   14 ++++----------
  1 file changed, 4 insertions(+), 10 deletions(-)

Index: linux-pm/drivers/acpi/internal.h
===================================================================
--- linux-pm.orig/drivers/acpi/internal.h
+++ linux-pm/drivers/acpi/internal.h
@@ -148,8 +148,11 @@ int acpi_wakeup_device_init(void);
  #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC
  void acpi_early_processor_control_setup(void);
  void acpi_early_processor_set_pdc(void);
-
+#ifdef CONFIG_X86
  void acpi_proc_quirk_mwait_check(void);
+#else
+static inline void acpi_proc_quirk_mwait_check(void) {}
+#endif
  bool processor_physically_present(acpi_handle handle);
  #else
  static inline void acpi_early_processor_control_setup(void) {}

```

For me this patch solves the build problem for v6.6-rc1 and -rc2.
There's also another patch available for that specific problem by Ard
([6]) but I haven't seen this one included either up until 42dc814 and I
also haven't tested this one.

Could one ([5]) or the other ([6]) please be included in v6.6 (or
earlier) to "fix" the build problem for ia64?

Cheers,
Frank


[3]:
https://github.com/torvalds/linux/commit/0a0e2ea642f6#diff-80c82874cec85e9c2facf52535b929ec62284c001ab081bfd1c1d164bf2a1d66R179

[4]:
https://lore.kernel.org/lkml/[email protected]/T/#u

[5]:
https://lore.kernel.org/lkml/CAJZ5v0hnNK4O_HyinvTp01YxXR7V4vzpMhf85yW9M2=52-O2Fg@mail.gmail.com/

[6]:
https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/commit/?id=a0334bf78b95532cec54f56b53e8ae1bfe7e1ca1