1.. SPDX-License-Identifier: GPL-2.0+
2.. Copyright (C) 2017, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
3
4QEMU ARM
5========
6
7QEMU for ARM supports a special 'virt' machine designed for emulation and
8virtualization purposes. This document describes how to run U-Boot under it.
9Both 32-bit ARM and AArch64 are supported.
10
11The 'virt' platform provides the following as the basic functionality:
12
13    - A freely configurable amount of CPU cores
14    - U-Boot loaded and executing in the emulated flash at address 0x0
15    - A generated device tree blob placed at the start of RAM
16    - A freely configurable amount of RAM, described by the DTB
17    - A PL011 serial port, discoverable via the DTB
18    - An ARMv7/ARMv8 architected timer
19    - PSCI for rebooting the system
20    - A generic ECAM-based PCI host controller, discoverable via the DTB
21
22Additionally, a number of optional peripherals can be added to the PCI bus.
23
24Building U-Boot
25---------------
26Set the CROSS_COMPILE environment variable as usual, and run:
27
28- For ARM::
29
30    make qemu_arm_defconfig
31    make
32
33- For AArch64::
34
35    make qemu_arm64_defconfig
36    make
37
38Running U-Boot
39--------------
40The minimal QEMU command line to get U-Boot up and running is:
41
42- For ARM::
43
44    qemu-system-arm -machine virt -bios u-boot.bin
45
46- For AArch64::
47
48    qemu-system-aarch64 -machine virt -cpu cortex-a57 -bios u-boot.bin
49
50Note that for some odd reason qemu-system-aarch64 needs to be explicitly
51told to use a 64-bit CPU or it will boot in 32-bit mode.
52
53Additional persistent U-boot environment support can be added as follows:
54
55- Create envstore.img using qemu-img::
56
57    qemu-img create -f raw envstore.img 64M
58
59- Add a pflash drive parameter to the command line::
60
61    -drive if=pflash,format=raw,index=1,file=envstore.img
62
63Additional peripherals that have been tested to work in both U-Boot and Linux
64can be enabled with the following command line parameters:
65
66- To add a Serial ATA disk via an Intel ICH9 AHCI controller, pass e.g.::
67
68    -drive if=none,file=disk.img,id=mydisk -device ich9-ahci,id=ahci -device ide-drive,drive=mydisk,bus=ahci.0
69
70- To add an Intel E1000 network adapter, pass e.g.::
71
72    -netdev user,id=net0 -device e1000,netdev=net0
73
74- To add an EHCI-compliant USB host controller, pass e.g.::
75
76    -device usb-ehci,id=ehci
77
78- To add a NVMe disk, pass e.g.::
79
80    -drive if=none,file=disk.img,id=mydisk -device nvme,drive=mydisk,serial=foo
81
82These have been tested in QEMU 2.9.0 but should work in at least 2.5.0 as well.
83
84Debug UART
85----------
86
87The debug UART on the ARM virt board uses these settings::
88
89    CONFIG_DEBUG_UART=y
90    CONFIG_DEBUG_UART_PL010=y
91    CONFIG_DEBUG_UART_BASE=0x9000000
92    CONFIG_DEBUG_UART_CLOCK=0
93