xref: /openbmc/qemu/docs/system/target-arm.rst (revision 2d30506d)
1.. _ARM-System-emulator:
2
3Arm System emulator
4-------------------
5
6QEMU can emulate both 32-bit and 64-bit Arm CPUs. Use the
7``qemu-system-aarch64`` executable to simulate a 64-bit Arm machine.
8You can use either ``qemu-system-arm`` or ``qemu-system-aarch64``
9to simulate a 32-bit Arm machine: in general, command lines that
10work for ``qemu-system-arm`` will behave the same when used with
11``qemu-system-aarch64``.
12
13QEMU has generally good support for Arm guests. It has support for
14nearly fifty different machines. The reason we support so many is that
15Arm hardware is much more widely varying than x86 hardware. Arm CPUs
16are generally built into "system-on-chip" (SoC) designs created by
17many different companies with different devices, and these SoCs are
18then built into machines which can vary still further even if they use
19the same SoC. Even with fifty boards QEMU does not cover more than a
20small fraction of the Arm hardware ecosystem.
21
22The situation for 64-bit Arm is fairly similar, except that we don't
23implement so many different machines.
24
25As well as the more common "A-profile" CPUs (which have MMUs and will
26run Linux) QEMU also supports "M-profile" CPUs such as the Cortex-M0,
27Cortex-M4 and Cortex-M33 (which are microcontrollers used in very
28embedded boards). For most boards the CPU type is fixed (matching what
29the hardware has), so typically you don't need to specify the CPU type
30by hand, except for special cases like the ``virt`` board.
31
32Choosing a board model
33======================
34
35For QEMU's Arm system emulation, you must specify which board
36model you want to use with the ``-M`` or ``--machine`` option;
37there is no default.
38
39Because Arm systems differ so much and in fundamental ways, typically
40operating system or firmware images intended to run on one machine
41will not run at all on any other. This is often surprising for new
42users who are used to the x86 world where every system looks like a
43standard PC. (Once the kernel has booted, most userspace software
44cares much less about the detail of the hardware.)
45
46If you already have a system image or a kernel that works on hardware
47and you want to boot with QEMU, check whether QEMU lists that machine
48in its ``-machine help`` output. If it is listed, then you can probably
49use that board model. If it is not listed, then unfortunately your image
50will almost certainly not boot on QEMU. (You might be able to
51extract the filesystem and use that with a different kernel which
52boots on a system that QEMU does emulate.)
53
54If you don't care about reproducing the idiosyncrasies of a particular
55bit of hardware, such as small amount of RAM, no PCI or other hard
56disk, etc., and just want to run Linux, the best option is to use the
57``virt`` board. This is a platform which doesn't correspond to any
58real hardware and is designed for use in virtual machines. You'll
59need to compile Linux with a suitable configuration for running on
60the ``virt`` board. ``virt`` supports PCI, virtio, recent CPUs and
61large amounts of RAM. It also supports 64-bit CPUs.
62
63Board-specific documentation
64============================
65
66Unfortunately many of the Arm boards QEMU supports are currently
67undocumented; you can get a complete list by running
68``qemu-system-aarch64 --machine help``.
69
70..
71   This table of contents should be kept sorted alphabetically
72   by the title text of each file, which isn't the same ordering
73   as an alphabetical sort by filename.
74
75.. toctree::
76   :maxdepth: 1
77
78   arm/integratorcp
79   arm/mps2
80   arm/musca
81   arm/realview
82   arm/sbsa
83   arm/versatile
84   arm/vexpress
85   arm/aspeed
86   arm/bananapi_m2u.rst
87   arm/b-l475e-iot01a.rst
88   arm/sabrelite
89   arm/highbank
90   arm/digic
91   arm/cubieboard
92   arm/emcraft-sf2
93   arm/musicpal
94   arm/gumstix
95   arm/mainstone
96   arm/kzm
97   arm/nseries
98   arm/nrf
99   arm/nuvoton
100   arm/imx25-pdk
101   arm/orangepi
102   arm/palm
103   arm/raspi
104   arm/xscale
105   arm/collie
106   arm/sx1
107   arm/stellaris
108   arm/stm32
109   arm/virt
110   arm/xenpvh
111   arm/xlnx-versal-virt
112   arm/xlnx-zynq
113
114Emulated CPU architecture support
115=================================
116
117.. toctree::
118   arm/emulation
119
120Arm CPU features
121================
122
123.. toctree::
124   arm/cpu-features
125