ACPI For 64-bit ARM Proposed For Linux 4.1

Going back many months there's been work on adding ACPI support to ARM64/AArch64. That long journey may now be wrapping up with a pending pull request for landing full ACPI support for 64-bit ARM in Linux 4.1.

Will Deacon sent in the "ACPI for arm64" pull request today with there already being 64-bit ARM hardware on the market that supports booting with ACPI tables -- or FDT tables. ACPI for ARM is possible in the latest revisions to the specification and Linaro has been focused on making the Advanced Configuration and Power Interface a reality for this x86 competitor.

This ACPI work allows for initializing CPUs, interrupt controller, and timers via ACPI tables while the memory information and rest are passed via EFI. While it's being mainlined now, ARM expects for the near future that users will continue defaulting to using the (non-ACPI) FDT table support. More ACPI 64-bit ARM improvements are expected once this big feature lands.

The pull request can be found here and just amounts to about 2K lines of new kernel code.