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	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>
		
			
				
	
	
		
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			127 lines
		
	
	
		
			3.6 KiB
		
	
	
	
		
			ReStructuredText
		
	
	
	
	
	
.. SPDX-License-Identifier: GPL-2.0+
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.. Copyright (C) 2017, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
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QEMU ARM
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========
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QEMU for ARM supports a special 'virt' machine designed for emulation and
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virtualization purposes. This document describes how to run U-Boot under it.
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Both 32-bit ARM and AArch64 are supported.
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The 'virt' platform provides the following as the basic functionality:
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    - A freely configurable amount of CPU cores
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    - U-Boot loaded and executing in the emulated flash at address 0x0
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    - A generated device tree blob placed at the start of RAM
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    - A freely configurable amount of RAM, described by the DTB
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    - A PL011 serial port, discoverable via the DTB
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    - An ARMv7/ARMv8 architected timer
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    - PSCI for rebooting the system
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    - A generic ECAM-based PCI host controller, discoverable via the DTB
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Additionally, a number of optional peripherals can be added to the PCI bus.
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See :doc:`../../develop/devicetree/dt_qemu` for information on how to see
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the devicetree actually generated by QEMU.
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Building U-Boot
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---------------
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Set the CROSS_COMPILE environment variable as usual, and run:
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- For ARM::
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    make qemu_arm_defconfig
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    make
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- For AArch64::
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    make qemu_arm64_defconfig
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    make
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Running U-Boot
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--------------
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The minimal QEMU command line to get U-Boot up and running is:
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- For ARM::
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    qemu-system-arm -machine virt -nographic -bios u-boot.bin
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- For AArch64::
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    qemu-system-aarch64 -machine virt -nographic -cpu cortex-a57 -bios u-boot.bin
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Note that for some odd reason qemu-system-aarch64 needs to be explicitly
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told to use a 64-bit CPU or it will boot in 32-bit mode. The -nographic argument
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ensures that output appears on the terminal. Use Ctrl-A X to quit.
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Additional persistent U-boot environment support can be added as follows:
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- Create envstore.img using qemu-img::
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    qemu-img create -f raw envstore.img 64M
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- Add a pflash drive parameter to the command line::
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    -drive if=pflash,format=raw,index=1,file=envstore.img
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Additional peripherals that have been tested to work in both U-Boot and Linux
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can be enabled with the following command line parameters:
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- To add a Serial ATA disk via an Intel ICH9 AHCI controller, pass e.g.::
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    -drive if=none,file=disk.img,format=raw,id=mydisk \
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    -device ich9-ahci,id=ahci -device ide-drive,drive=mydisk,bus=ahci.0
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- To add an Intel E1000 network adapter, pass e.g.::
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    -netdev user,id=net0 -device e1000,netdev=net0
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- To add an EHCI-compliant USB host controller, pass e.g.::
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    -device usb-ehci,id=ehci
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- To add an NVMe disk, pass e.g.::
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    -drive if=none,file=disk.img,id=mydisk -device nvme,drive=mydisk,serial=foo
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- To add a random number generator, pass e.g.::
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    -device virtio-rng-pci
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These have been tested in QEMU 2.9.0 but should work in at least 2.5.0 as well.
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Enabling TPMv2 support
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----------------------
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To emulate a TPM the swtpm package may be used. It can be built from the
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following repositories:
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     https://github.com/stefanberger/swtpm.git
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Swtpm provides a socket for the TPM emulation which can be consumed by QEMU.
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In a first console invoke swtpm with::
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     swtpm socket --tpmstate dir=/tmp/mytpm1   \
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     --ctrl type=unixio,path=/tmp/mytpm1/swtpm-sock --log level=20
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In a second console invoke qemu-system-aarch64 with::
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     -chardev socket,id=chrtpm,path=/tmp/mytpm1/swtpm-sock \
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     -tpmdev emulator,id=tpm0,chardev=chrtpm \
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     -device tpm-tis-device,tpmdev=tpm0
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Enable the TPM on U-Boot's command line with::
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    tpm2 startup TPM2_SU_CLEAR
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Debug UART
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----------
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The debug UART on the ARM virt board uses these settings::
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    CONFIG_DEBUG_UART=y
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    CONFIG_DEBUG_UART_PL010=y
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    CONFIG_DEBUG_UART_BASE=0x9000000
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    CONFIG_DEBUG_UART_CLOCK=0
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