Re: [PATCH v6 04/10] x86/dt: Parse the Wakeup Mailbox for Intel processors

[Wei Liu <wei.liu@kernel.org>]

On Thu, Oct 16, 2025 at 07:57:26PM -0700, Ricardo Neri wrote:
> The Wakeup Mailbox is a mechanism to boot secondary CPUs on systems that do
> not want or cannot use the INIT + StartUp IPI messages.
> 
> The platform firmware is expected to implement the mailbox as described in
> the Multiprocessor Wakeup Structure of the ACPI specification. It is also
> expected to publish the mailbox to the operating system as described in the
> corresponding DeviceTree schema that accompanies the documentation of the
> Linux kernel.
> 
> Reuse the existing functionality to set the memory location of the mailbox
> and update the wakeup_secondary_cpu_64() APIC callback. Make this
> functionality available to DeviceTree-based systems by making CONFIG_X86_
> MAILBOX_WAKEUP depend on either CONFIG_OF or CONFIG_ACPI_MADT_WAKEUP.
> 
> do_boot_cpu() uses wakeup_secondary_cpu_64() when set. It will be set if a
> wakeup mailbox is enumerated via an ACPI table or a DeviceTree node. For
> cases in which this behavior is not desired, this APIC callback can be
> updated later during boot using platform-specific hooks.
> 
> Reviewed-by: Dexuan Cui <decui@microsoft.com>
> Co-developed-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>
> Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>

Can I get an ack from x86 maintainers?

Wei