This package demonstrates an AArch64 UEFI implementation for hacked Lumia 950 and Lumia 950 XL. Currently it is able to boot Windows 10 ARM64 (with a minor patch). Booting Linux is also possible (see the note).

I am too busy to write an average-user instruction. So if you are interested in, you are welcome to contribute to an easy instruction for all Lumia 950 XL users.

Or you can buy me a coffee: PayPal.

If you are familar with EDK2, you don't need to use my build script.

• Checkout a copy of EDK2, then checkout this repository under EDK2's worktree.
• Commit 0e2a5749d89c96e3e17ea458365d2e5296c807e2 absoultely works for you.
• Install Linaro AArch64 GCC toolchains, my build script uses gcc-linaro-7.2.1-2017.11. Then untar them. I place everything under /opt directory, so I have directories like /opt/gcc-linaro-7.2.1-2017.11-x86_64_aarch64-elf/bin. If you placed it somewhere else, modify build scripts.
• Copy rundbbuild.sh in Tools directory to your EDK2 worktree root directory.
• Export variable GCC5_AARCH64_PREFIX to your GCC directory with prefix (e.g. /opt/gcc-linaro-7.2.1-2017.11-x86_64_aarch64-elf/bin/aarch64-elf-)
• Start build: . rundbbuild.sh --950xl --development

Per UEFI specification, ARM32 UEFI cannot boot ARM64 binaries directly. A recent engineering change removed the dependency of Little Kernel. LK can still boot it, but the path is untested.

To run this UEFI build on Lumia 950 XL, the following procedure is required:

• Check out Boot Shim. This Boot Manager Application implements a simple ELF loader for the kickstarter (LK) with Secure Monitor Call for EL1 transition. You will need branch msm8994-aa64.
• Place UEFI.elf in the WP EFIESP root directory, copy Boot Shim EFI appliction to the EFIESP partition, create a new BCD entry for it.
• Select this boot entry to enter UEFI.

To re-flash UEFI, simply place new UEFI.elf in WP EFIESP root directory.

You don't need the patch anymore. If you have applied the patch, you should change it back in MdePkg/Include/AArch64/ProcessorBind.h.

Qualcomm Snapdragon MSM8992/MSM8994 implements a subset of PSCI interface for multi-processor startup. However, required commands like PSCI_SYSTEM_OFF and PSCI_SYSTEM_RESET are not implemented. Hence we use PMIC to shutdown platform (there's a bug in RT that will be fixed) instead of PSCI. Additionally, 8992/8994 uses HVC call for PSCI commands instead of SMC call. It seems that Linux encounters some troubles during MP startup.

The ACPI tables are copied from stock Windows Phone FFU, hence these device IDs are likely not be recognized by Linux.

To get started, starts with the device tree of Qualcomm MSM8994 MTP. The repository devicetree-rebasing with DT content from Android Linux Kernel is sufficient for DT development. To boot with device tree, add it in your GRUB configuration:

devicetree /lumia-950-xl.dtb
linux /vmlinuz ..... acpi=no

PSCI partially works. If you want to use PSCI for multi-processor startup, add the following code to your DT:

psci {
	compatible	= "arm,psci-0.2";
	method		= "hvc";
};

And use psci for core-enable method. I think the MSM8994 Cortex ACC method works if you are working on a kernel for MSM8994, but I have not tested it yet.

• EFIDroid Project
• Andrei Warkentin and his RaspberryPiPkg
• Sarah Purohit
• Googulator

All code except drivers in GPLDriver directory are licensed under BSD 2-Clause. GPL Drivers are licensed under GPLv2 license.