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16736c2312
Provide settings for enabling the debug UART of the virt machine on RISC-V QEMU. Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
145 lines
4.8 KiB
ReStructuredText
145 lines
4.8 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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.. Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
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QEMU RISC-V
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===========
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QEMU for RISC-V supports a special 'virt' machine and 'spike' machine designed
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for emulation and virtualization purposes. This document describes how to run
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U-Boot under it. Both 32-bit and 64-bit targets are supported, running in
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either machine or supervisor mode.
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The QEMU virt machine models a generic RISC-V virtual machine with support for
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the VirtIO standard networking and block storage devices. It has CLINT, PLIC,
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16550A UART devices in addition to VirtIO and it also uses device-tree to pass
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configuration information to guest software. It implements the latest RISC-V
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privileged architecture.
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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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The QEMU spike machine models a minimalistic RISC-V virtual machine with
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only CLINT and HTIF devices. It also uses device-tree to pass configuration
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information to guest software and implements the latest RISC-V privileged
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architecture.
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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 32-bit RISC-V::
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make qemu-riscv32_defconfig
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make
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- For 64-bit RISC-V::
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make qemu-riscv64_defconfig
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make
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This will compile U-Boot for machine mode. To build supervisor mode binaries,
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use the configurations qemu-riscv32_smode_defconfig and
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qemu-riscv64_smode_defconfig instead. Note that U-Boot running in supervisor
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mode requires a supervisor binary interface (SBI), such as RISC-V OpenSBI.
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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 32-bit RISC-V virt machine::
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qemu-system-riscv32 -nographic -machine virt -bios u-boot.bin
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- For 64-bit RISC-V virt machine::
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qemu-system-riscv64 -nographic -machine virt -bios u-boot.bin
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- For 64-bit RISC-V spike machine::
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qemu-system-riscv64 -nographic -machine spike -bios u-boot.bin
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The commands above create targets with 128MiB memory by default.
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A freely configurable amount of RAM can be created via the '-m'
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parameter. For example, '-m 2G' creates 2GiB memory for the target,
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and the memory node in the embedded DTB created by QEMU reflects
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the new setting.
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For instructions on how to run U-Boot in supervisor mode on QEMU
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with OpenSBI, see the documentation available with OpenSBI:
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https://github.com/riscv/opensbi/blob/master/docs/platform/qemu_virt.md
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https://github.com/riscv/opensbi/blob/master/docs/platform/spike.md
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These have been tested in QEMU 5.0.0.
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Running U-Boot SPL
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------------------
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In the default SPL configuration, U-Boot SPL starts in machine mode. U-Boot
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proper and OpenSBI (FW_DYNAMIC firmware) are bundled as FIT image and made
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available to U-Boot SPL. Both are then loaded by U-Boot SPL and the location
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of U-Boot proper is passed to OpenSBI. After initialization, U-Boot proper is
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started in supervisor mode by OpenSBI.
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OpenSBI must be compiled before compiling U-Boot. Version 0.4 and higher is
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supported by U-Boot. Clone the OpenSBI repository and run the following command.
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.. code-block:: console
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git clone https://github.com/riscv/opensbi.git
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cd opensbi
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make PLATFORM=generic
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See the OpenSBI documentation for full details:
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https://github.com/riscv/opensbi/blob/master/docs/platform/qemu_virt.md
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https://github.com/riscv/opensbi/blob/master/docs/platform/spike.md
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To make the FW_DYNAMIC binary (build/platform/generic/firmware/fw_dynamic.bin)
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available to U-Boot, either copy it into the U-Boot root directory or specify
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its location with the OPENSBI environment variable. Afterwards, compile U-Boot
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with the following commands.
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- For 32-bit RISC-V::
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make qemu-riscv32_spl_defconfig
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make
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- For 64-bit RISC-V::
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make qemu-riscv64_spl_defconfig
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make
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The minimal QEMU commands to run U-Boot SPL in both 32-bit and 64-bit
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configurations are:
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- For 32-bit RISC-V virt machine::
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qemu-system-riscv32 -nographic -machine virt -bios spl/u-boot-spl.bin \
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-device loader,file=u-boot.itb,addr=0x80200000
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- For 64-bit RISC-V virt machine::
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qemu-system-riscv64 -nographic -machine virt -bios spl/u-boot-spl.bin \
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-device loader,file=u-boot.itb,addr=0x80200000
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- For 64-bit RISC-V spike machine::
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qemu-system-riscv64 -nographic -machine spike -bios spl/u-boot-spl.bin \
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-device loader,file=u-boot.itb,addr=0x80200000
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An attached disk can be emulated in RISC-V virt machine by adding::
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-device ich9-ahci,id=ahci \
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-drive if=none,file=riscv64.img,format=raw,id=mydisk \
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-device ide-hd,drive=mydisk,bus=ahci.0
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You will have to run 'scsi scan' to use it.
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Debug UART
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----------
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The following settings provide a debug UART for the virt machine::
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CONFIG_DEBUG_UART=y
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CONFIG_DEBUG_UART_NS16550=y
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CONFIG_DEBUG_UART_BASE=0x10000000
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CONFIG_DEBUG_UART_CLOCK=3686400
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