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

[Toshi Kani <toshi.kani@hp.com>]

On Wed, 2015-06-10 at 01:48 +0200, Rafael J. Wysocki wrote:
> On Wednesday, June 03, 2015 11:13:57 AM Toshi Kani wrote:
> > 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().)
> 
> OK, update follows.

Very helpful.  Thanks for the update.
-Toshi