[PATCH v2] ARM64: kernel: implement ACPI parking protocol

Catalin Marinas catalin.marinas at arm.com
Tue Oct 6 09:50:50 PDT 2015

On Thu, Sep 10, 2015 at 06:40:22PM +0100, Lorenzo Pieralisi wrote:
> The SBBR and ACPI specifications allow ACPI based systems that do not
> implement PSCI (eg systems with no EL3) to boot through the ACPI parking
> protocol specification[1].
> This patch implements the ACPI parking protocol CPU operations, and adds
> code that eases parsing the parking protocol data structures to the
> ARM64 SMP initializion carried out at the same time as cpus enumeration.
> To wake-up the CPUs from the parked state, this patch implements a
> wakeup IPI for ARM64 (ie arch_send_wakeup_ipi_mask()) that mirrors the
> ARM one, so that a specific IPI is sent for wake-up purpose in order
> to distinguish it from other IPI sources.
> Given the current ACPI MADT parsing API, the patch implements a glue
> layer that helps passing MADT GICC data structure from SMP initialization
> code to the parking protocol implementation somewhat overriding the CPU
> operations interfaces. This to avoid creating a completely trasparent
> DT/ACPI CPU operations layer that would require creating opaque
> structure handling for CPUs data (DT represents CPU through DT nodes, ACPI
> through static MADT table entries), which seems overkill given that ACPI
> on ARM64 mandates only two booting protocols (PSCI and parking protocol),
> so there is no need for further protocol additions.
> Based on the original work by Mark Salter <msalter at redhat.com>
> [1] https://acpica.org/sites/acpica/files/MP%20Startup%20for%20ARM%20platforms.docx

Question to Lorenzo and Mark Salter: was this patch successfully tested
on real hardware (like Applied X-Gene)?



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