Patrick Rudolph <patrick.rudolph@9elements.com> says:

Based on the existing work done by Simon Glass this series adds
support for booting aarch64 devices using ACPI only.
As first target QEMU SBSA support is added, which relies on ACPI
only to boot an OS. As secondary target the Raspberry Pi4 was used,
which is broadly available and allows easy testing of the proposed
solution.

The series is split into ACPI cleanups and code movements, adding
Arm specific ACPI tables and finally SoC and mainboard related
changes to boot a Linux on the QEMU SBSA and RPi4. Currently only the
mandatory ACPI tables are supported, allowing to boot into Linux
without errors.

The QEMU SBSA support is feature complete and provides the same
functionality as the EDK2 implementation.

The changes were tested on real hardware as well on QEMU v9.0:

qemu-system-aarch64 -machine sbsa-ref -nographic -cpu cortex-a57 \
                    -pflash secure-world.rom \
                    -pflash unsecure-world.rom

qemu-system-aarch64 -machine raspi4b -kernel u-boot.bin -cpu cortex-a72 \
-smp 4 -m 2G -drive file=raspbian.img,format=raw,index=0 \
-dtb bcm2711-rpi-4-b.dtb -nographic

Tested against FWTS V24.03.00.

Known issues:
- The QEMU rpi4 support is currently limited as it doesn't emulate PCI,
  USB or ethernet devices!
- The SMP bringup doesn't work on RPi4, but works in QEMU (Possibly
  cache related).
- PCI on RPI4 isn't working on real hardware since the pcie_brcmstb
  Linux kernel module doesn't support ACPI yet.

Link: https://lore.kernel.org/r/20241023132116.970117-1-patrick.rudolph@9elements.com