On Wed, Oct 29, 2025 at 12:13:58PM +0100, Borislav Petkov wrote:
> On Mon, Oct 27, 2025 at 01:58:16PM -0700, Ricardo Neri wrote:
> > Right. All the functions in the file start with the acpi_ prefix. It could
> > be kept under arch/x86/kernel/acpi/. The Kconfig symbol X86_MAILBOX_WAKEUP
> > would have to live in arch/x86/Kconfig as there is no Kconfig file under
> > arch/x86/kernel/acpi. ACPI_MADT_WAKEUP is arch/x86/Kconfig.
> > 
> > Does that sound acceptable?
> 
> Right, this looks kinda weird. You have devicetree thing using ACPI code,
> you're trying to carve it out but then it is ACPI code anyway. So why even do
> that?
> 
> You can simply leave ACPI enabled on that configuration. I don't see yet what
> the point for the split is - saving memory, or...?

I did not want to enable the whole of ACPI code as I need a tiny portion of it.
Then yes, saving memory and having a smaller binary were considerations.

The only dependency that ACPI_MADT_WAKEUP has on ACPI is the code to read and
parse the ACPI table that enumerates the mailbox. (There are a couple of
declarations for CPU offlining that need tweaking if I want ACPI_MADT_WAKEUP to
not depend on ACPI at all).

The DeviceTree firmware only needs the code to wake CPUs up. That is the code
I am carving out.

Having said that, vmlinux and bzImage increase by 4% if I enable ACPI.

Thanks and BR,
Ricardo

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