u-boot/doc/board/emulation/qemu-arm.rst
Simon Glass c3c1614537 arm: riscv: qemu: Explain how to extract the generated dt
QEMU currently generates a devicetree for use with U-Boot. Explain how to
obtain it.

Also explain how to merge it to produce a devicetree with the U-Boot
features included.

Signed-off-by: Simon Glass <sjg@chromium.org>
2021-12-23 10:24:39 -05:00

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.. SPDX-License-Identifier: GPL-2.0+
.. Copyright (C) 2017, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
QEMU ARM
========
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.
See :doc:`../../develop/devicetree/dt_qemu` for information on how to see
the devicetree actually generated by QEMU.
Building U-Boot
---------------
Set the CROSS_COMPILE environment variable as usual, and run:
- For ARM::
make qemu_arm_defconfig
make
- For AArch64::
make qemu_arm64_defconfig
make
Running U-Boot
--------------
The minimal QEMU command line to get U-Boot up and running is:
- For ARM::
qemu-system-arm -machine virt -nographic -bios u-boot.bin
- For AArch64::
qemu-system-aarch64 -machine virt -nographic -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. The -nographic argument
ensures that output appears on the terminal. Use Ctrl-A X to quit.
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::
-drive if=pflash,format=raw,index=1,file=envstore.img
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,format=raw,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.::
-device usb-ehci,id=ehci
- To add an NVMe disk, pass e.g.::
-drive if=none,file=disk.img,id=mydisk -device nvme,drive=mydisk,serial=foo
- To add a random number generator, pass e.g.::
-device virtio-rng-pci
These have been tested in QEMU 2.9.0 but should work in at least 2.5.0 as well.
Enabling TPMv2 support
----------------------
To emulate a TPM the swtpm package may be used. It can be built from the
following repositories:
https://github.com/stefanberger/swtpm.git
Swtpm provides a socket for the TPM emulation which can be consumed by QEMU.
In a first console invoke swtpm with::
swtpm socket --tpmstate dir=/tmp/mytpm1 \
--ctrl type=unixio,path=/tmp/mytpm1/swtpm-sock --log level=20
In a second console invoke qemu-system-aarch64 with::
-chardev socket,id=chrtpm,path=/tmp/mytpm1/swtpm-sock \
-tpmdev emulator,id=tpm0,chardev=chrtpm \
-device tpm-tis-device,tpmdev=tpm0
Enable the TPM on U-Boot's command line with::
tpm2 startup TPM2_SU_CLEAR
Debug UART
----------
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