1# SPDX-License-Identifier: GPL-2.0+ 2# 3# Copyright (C) 2017, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi> 4 5U-Boot on QEMU's 'virt' machine on ARM & AArch64 6================================================ 7 8QEMU for ARM supports a special 'virt' machine designed for emulation and 9virtualization purposes. This document describes how to run U-Boot under it. 10Both 32-bit ARM and AArch64 are supported. 11 12The 'virt' platform provides the following as the basic functionality: 13 14 - A freely configurable amount of CPU cores 15 - U-Boot loaded and executing in the emulated flash at address 0x0 16 - A generated device tree blob placed at the start of RAM 17 - A freely configurable amount of RAM, described by the DTB 18 - A PL011 serial port, discoverable via the DTB 19 - An ARMv7/ARMv8 architected timer 20 - PSCI for rebooting the system 21 - A generic ECAM-based PCI host controller, discoverable via the DTB 22 23Additionally, a number of optional peripherals can be added to the PCI bus. 24 25Building U-Boot 26--------------- 27Set the CROSS_COMPILE environment variable as usual, and run: 28 29- For ARM: 30 make qemu_arm_defconfig 31 make 32 33- For AArch64: 34 make qemu_arm64_defconfig 35 make 36 37Running U-Boot 38-------------- 39The minimal QEMU command line to get U-Boot up and running is: 40 41- For ARM: 42 qemu-system-arm -machine virt -bios u-boot.bin 43 44- For AArch64: 45 qemu-system-aarch64 -machine virt -cpu cortex-a57 -bios u-boot.bin 46 47Note that for some odd reason qemu-system-aarch64 needs to be explicitly 48told to use a 64-bit CPU or it will boot in 32-bit mode. 49 50Additional persistent U-boot environment support can be added as follows: 51- Create envstore.img using qemu-img: 52 qemu-img create -f raw envstore.img 64M 53- Add a pflash drive parameter to the command line: 54 -drive if=pflash,format=raw,index=1,file=envstore.img 55 56Additional peripherals that have been tested to work in both U-Boot and Linux 57can be enabled with the following command line parameters: 58 59- To add a Serial ATA disk via an Intel ICH9 AHCI controller, pass e.g.: 60 -drive if=none,file=disk.img,id=mydisk -device ich9-ahci,id=ahci -device ide-drive,drive=mydisk,bus=ahci.0 61- To add an Intel E1000 network adapter, pass e.g.: 62 -netdev user,id=net0 -device e1000,netdev=net0 63- To add an EHCI-compliant USB host controller, pass e.g.: 64 -device usb-ehci,id=ehci 65- To add a NVMe disk, pass e.g.: 66 -drive if=none,file=disk.img,id=mydisk -device nvme,drive=mydisk,serial=foo 67 68These have been tested in QEMU 2.9.0 but should work in at least 2.5.0 as well. 69