Re: [PATCH] ACPI / init: Switch over platform to the ACPI mode later

Toshi Kani
2015-06-03T17:33:43Z

On Sat, 2015-05-30 at 14:21 +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Commit 73f7d1ca3263 "ACPI / init: Run acpi_early_init() before
> timekeeping_init()" moved the ACPI subsystem initialization,
> including the ACPI mode enabling, to an earlier point in the
> initialization sequence, to allow the timekeeping subsystem
> use ACPI early. Unfortunately, that resulted in boot regressions
> on some systems and the early ACPI initialization was moved toward
> its original position in the kernel initialization code by commit
> c4e1acbb35e4 "ACPI / init: Invoke early ACPI initialization later".
>
> However, that turns out to be insufficient, as boot is still broken
> on the Tyan S8812 mainboard.
>
> To fix that issue, split the ACPI early initialization code into
> two pieces so the majority of it still located in acpi_early_init()
> and the part switching over the platform into the ACPI mode goes into
> a new function, acpi_subsystem_init(), executed at the original early
> ACPI initialization spot.
>
> That fixes the Tyan S8812 boot problem, but still allows ACPI
> tables to be loaded earlier which is useful to the EFI code in
> efi_enter_virtual_mode().
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=97141
> Reported-and-tested-by: Marius Tolzmann <tolzmann@molgen.mpg.de>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Can you add comments to acpi_early_init() and acpi_subsystem_init() to
clarify what ACPI features are enabled at each phase, and what
dependency they have in the boot sequence? (The same goes to
early_acpi_boot_init() and acpi_boot_init().)

Otherwise, the change looks good.

Acked-by: Toshi Kani <toshi.kani@hp.com>

Thanks,
-Toshi