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Provide the settings for the debug UART on the QEMU ARM virt board. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
93 lines
2.6 KiB
ReStructuredText
93 lines
2.6 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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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 -bios u-boot.bin
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- For AArch64::
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qemu-system-aarch64 -machine virt -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.
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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,id=mydisk -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 a 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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These have been tested in QEMU 2.9.0 but should work in at least 2.5.0 as well.
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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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