Re: [PATCH v3 0/7] ACPI: Add _OST support for ACPI hotplug

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

On Fri, 2012-05-11 at 10:09 -0700, Andi Kleen wrote:
> Toshi Kani <toshi.kani@hp.com> writes:
> 
> > This patchset supports ACPI OSPM Status Indication (_OST) method for
> > ACPI CPU/memory/container hotplug operations and sysfs eject. After
> > ACPI hotplug operation has completed, OSPM calls _OST to indicate the
> > result of the operation to the platform. If _OST is not present, this
> > patchset has no effect on the platform.
> >
> > This _OST support can be enabled or disabled with a new config option
> > CONFIG_ACPI_HOTPLUG_OST. This option is disabled by default. When
> > this option is disabled, this patchset has no effect on the platform.
> 
> Does that control compiling in/out significant sized code?
> 
> Controlling code behaviour by CONFIG option has been long deprecated.
> This is always better done as a runtime option.
> 
> Just think what should a distribution who wants to use the same binary
> on all systems set.

Good question.  The OS needs to tell the platform if it supports _OST at
boot-time, and has to stick with it.  Therefore, this feature may not be
enabled/disabled during run-time.  Another reason is that this feature
depends on ACPI_HOTPLUG_CPU, ACPI_HOTPLUG_MEMORY and ACPI_CONTAINER
config options in order to provide consistent behavior among multiple
hotplug operations with regarding the _OST support.

Thanks,
-Toshi