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Commit 220b0d8b authored by James Morse's avatar James Morse
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ACPI: Add _OSC bits to advertise OS support for toggling CPU present/enabled


Platform firmware can disabled a CPU, or make it not-present by calling
_EJ0 to make it offline, then changing _STA with the new status.

Not all operating systems support this. For arm64 making CPUs not-present
has never been supported. For all ACPI architectures, making CPUs disabled
has recently been added. Firmware can't know what the OS has support for.

Add two new _OSC bits to advertise whether the OS supports the _STA enabled
or present bits being toggled for CPUs. This will be important for arm64
if systems that support physical CPU hotplug ever appear as arm64 linux
doesn't currently support this, so firmware shouldn't try.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
---
I'm assuming ia64 with physical hotplug machines once existed, and
that Loongarch machines with support for this don't.
parent 8e3e891c
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