QEMU for ARM supports a special ‘virt’ machine designed for emulation and virtualization purposes. This document describes how to run U-Boot under it. Both 32-bit ARM and AArch64 are supported.
The ‘virt’ 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 0x0
- A generated device tree blob placed at the start of RAM
- A freely configurable amount of RAM, described by the DTB
- A PL011 serial port, discoverable via the DTB
- An ARMv7/ARMv8 architected timer
- PSCI for rebooting the system
- A generic ECAM-based PCI host controller, discoverable via the DTB
Additionally, a number of optional peripherals can be added to the PCI bus.
Set the CROSS_COMPILE environment variable as usual, and run:
make qemu_arm_defconfig make
make qemu_arm64_defconfig make
The minimal QEMU command line to get U-Boot up and running is:
qemu-system-arm -machine virt -bios u-boot.bin
qemu-system-aarch64 -machine virt -cpu cortex-a57 -bios u-boot.bin
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.
Additional persistent U-boot environment support can be added as follows:
Create envstore.img using qemu-img:
qemu-img create -f raw envstore.img 64M
Add a pflash drive parameter to the command line:
Additional peripherals that have been tested to work in both U-Boot and Linux can be enabled with the following command line parameters:
To add a Serial ATA disk via an Intel ICH9 AHCI controller, pass e.g.:
-drive if=none,file=disk.img,id=mydisk -device ich9-ahci,id=ahci -device ide-drive,drive=mydisk,bus=ahci.0
To add an Intel E1000 network adapter, pass e.g.:
-netdev user,id=net0 -device e1000,netdev=net0
To add an EHCI-compliant USB host controller, pass e.g.:
To add a NVMe disk, pass e.g.:
-drive if=none,file=disk.img,id=mydisk -device nvme,drive=mydisk,serial=foo
These have been tested in QEMU 2.9.0 but should work in at least 2.5.0 as well.
The debug UART on the ARM virt board uses these settings:
CONFIG_DEBUG_UART=y CONFIG_DEBUG_UART_PL010=y CONFIG_DEBUG_UART_BASE=0x9000000 CONFIG_DEBUG_UART_CLOCK=0