QEMU ARM SBSA

QEMU for ARM supports Arm Server Base System Architecture Reference board, short ‘sbsa-ref’ that utilizes ACPI over FDT. This document describes how to run U-Boot under it. Only AArch64 is supported.

The ‘sbsa’ platform provides the following as the basic functionality:

A freely configurable amount of CPU cores

U-Boot loaded and executing in the emulated flash at address 0x10000000

No device tree blob

A freely configurable amount of RAM

A PL011 serial port

An ARMv7/ARMv8 architected timer

PSCI for rebooting the system

A generic ECAM-based PCI host controller

Additionally, a number of optional peripherals can be added to the PCI bus.

Compile ARM Trusted Firmware (ATF)

Get and Build the ARM Trusted firmware

Note: srctree is U-Boot source directory Get ATF from: https://github.com/ARM-software/arm-trusted-firmware

git clone https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git tfa
cd tfa
make CROSS_COMPILE=aarch64-linux-gnu- all fip \
  ARM_LINUX_KERNEL_AS_BL33=1 DEBUG=1 PLAT=qemu_sbsa

Copy the resulting FIP and BL1 binary

cp build/qemu_sbsa/debug/fip.bin ../
cp build/qemu_sbsa/debug/bl1.bin ../

Building U-Boot

Set the CROSS_COMPILE environment variable as usual, and run:

make qemu-arm-sbsa_defconfig
make

Running U-Boot

The minimal QEMU command line to get U-Boot up and running is:

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

Note that for some odd reason qemu-system-aarch64 needs to be explicitly told to use a 64-bit CPU or it will boot in 32-bit mode. The -nographic argument ensures that output appears on the terminal. Use Ctrl-A X to quit.

Booting distros

It is possible to install and boot a standard Linux distribution using sbsa by setting up a root disk:

.. code-block:: bash

qemu-img create root.img 20G

then using the installer to install. For example, with Debian 12:

.. code-block:: bash

qemu-system-aarch64
-machine sbsa-ref -cpu cortex-a57 -m 4G -smp 4 -pflash secure-world.rom -pflash unsecure-world.rom -device virtio-rng-pci -device usb-kbd -device usb-tablet -cdrom debian-12.0.0-arm64-netinst.iso -hda root.img

Debug UART

The debug UART on the ARM sbsa board uses these settings:

CONFIG_DEBUG_UART=y