mainboard/emulation/qemu-aarch64: Add new board for ARMv8

This CL adds a new board, QEMU/AArch64, for ARMv8. The machine supported
is virt which is a QEMU 2.8 ARM virtual machine. The default CPU of
qemu-system-aarch64 is Cortex-a15, so you need to specify a 64-bit cpu
via a flag.

To execute:
$ qemu-system-aarch64 -M virt,secure=on,virtualization=on \
  -cpu cortex-a53 -bios build/coreboot.rom -m 8192M -nographic

Change-Id: Id7c0831b1ecf08785b4ec8139d809bad9b3e1eec
Signed-off-by: Asami Doi <d0iasm.pub@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33387
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/Documentation/mainboard/emulation/qemu-aarch64.md b/Documentation/mainboard/emulation/qemu-aarch64.md
new file mode 100644
index 0000000000..ee4c9e7a3b
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+# QEMU AArch64 emulator
+This page discribes how to build and run coreboot for QEMU/AArch64.
+You can use LinuxBoot via `make menuconfig` or an arbitrary FIT image
+as a payload for QEMU/AArch64.
+
+## Running coreboot in QEMU
+```bash
+qemu-system-aarch64 -bios ./build/coreboot.rom \
+    -M virt,secure=on,virtualization=on -cpu cortex-a53 \
+    -nographic -m 8912M
+```
+
+- The default CPU in QEMU for AArch64 is a cortex-a15 which is 32-bit
+ARM CPU. You need to specify 64-bit ARM CPU via `-cpu cortex-a53`.
+- The default privilege level in QEMU for AArch64 is EL1 that we can't
+have the right to access EL3/EL2 registers. You need to enable EL3/EL2
+via `-machine secure=on,virtualization=on`.
+- You need to specify the size of memory more than 544 MiB because 512
+MiB is reserved for the kernel.
+
+## Building coreboot with an arbitrary FIT payload
+There are 3 steps to make coreboot.rom for QEMU/AArch64. If you select
+LinuxBoot, step 2 and 3 have done by LinuxBoot.
+1. Get a DTB (Device Tree Blob)
+2. Build a FIT image with a DTB
+3. Add a FIT image to coreboot.rom
+
+### 1. Get a DTB
+You can get the DTB from QEMU with the following command.
+```
+$ qemu-system-aarch64 \
+    -M virt,dumpdtb=virt.dtb,secure=on,virtualization=on \
+    -cpu cortex-a53 -nographic -m 2048M
+```
+
+### 2. Build a FIT image with a DTB
+You need to write an image source file that has an `.its` extension to
+configure kernels, ramdisks, and DTBs.
+See [Flattened uImage Tree documentation](../../lib/payloads/fit.md) for more details.
+
+### 3. Add a FIT image to coreboot.rom
+You can use cbfstool to add the payload you created in step 2 to
+the coreboot.rom.
+```
+$ ./build/cbfstool ./build/coreboot.rom add -f <path-to-a-payload>/uImage \
+    -n fallback/payload -t fit -c lzma
+```