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+.. SPDX-License-Identifier: GPL-2.0+
+.. Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+
+QEMU RISC-V
+===========
+
+QEMU for RISC-V supports a special 'virt' machine designed for emulation and
+virtualization purposes. This document describes how to run U-Boot under it.
+Both 32-bit and 64-bit targets are supported, running in either machine or
+supervisor mode.
+
+The QEMU virt machine models a generic RISC-V virtual machine with support for
+the VirtIO standard networking and block storage devices. It has CLINT, PLIC,
+16550A UART devices in addition to VirtIO and it also uses device-tree to pass
+configuration information to guest software. It implements RISC-V privileged
+architecture spec v1.10.
+
+Building U-Boot
+---------------
+Set the CROSS_COMPILE environment variable as usual, and run:
+
+- For 32-bit RISC-V::
+
+    make qemu-riscv32_defconfig
+    make
+
+- For 64-bit RISC-V::
+
+    make qemu-riscv64_defconfig
+    make
+
+This will compile U-Boot for machine mode. To build supervisor mode binaries,
+use the configurations qemu-riscv32_smode_defconfig and
+qemu-riscv64_smode_defconfig instead. Note that U-Boot running in supervisor
+mode requires a supervisor binary interface (SBI), such as RISC-V OpenSBI.
+
+Running U-Boot
+--------------
+The minimal QEMU command line to get U-Boot up and running is:
+
+- For 32-bit RISC-V::
+
+    qemu-system-riscv32 -nographic -machine virt -bios u-boot
+
+- For 64-bit RISC-V::
+
+    qemu-system-riscv64 -nographic -machine virt -bios u-boot
+
+The commands above create targets with 128MiB memory by default.
+A freely configurable amount of RAM can be created via the '-m'
+parameter. For example, '-m 2G' creates 2GiB memory for the target,
+and the memory node in the embedded DTB created by QEMU reflects
+the new setting.
+
+For instructions on how to run U-Boot in supervisor mode on QEMU
+with OpenSBI, see the documentation available with OpenSBI:
+https://github.com/riscv/opensbi/blob/master/docs/platform/qemu_virt.md
+
+These have been tested in QEMU 5.0.0.
+
+Running U-Boot SPL
+------------------
+In the default SPL configuration, U-Boot SPL starts in machine mode. U-Boot
+proper and OpenSBI (FW_DYNAMIC firmware) are bundled as FIT image and made
+available to U-Boot SPL. Both are then loaded by U-Boot SPL and the location
+of U-Boot proper is passed to OpenSBI. After initialization, U-Boot proper is
+started in supervisor mode by OpenSBI.
+
+OpenSBI must be compiled before compiling U-Boot. Version 0.4 and higher is
+supported by U-Boot. Clone the OpenSBI repository and run the following command.
+
+.. code-block:: console
+
+    git clone https://github.com/riscv/opensbi.git
+    cd opensbi
+    make PLATFORM=generic
+
+See the OpenSBI documentation for full details:
+https://github.com/riscv/opensbi/blob/master/docs/platform/qemu_virt.md
+
+To make the FW_DYNAMIC binary (build/platform/qemu/virt/firmware/fw_dynamic.bin)
+available to U-Boot, either copy it into the U-Boot root directory or specify
+its location with the OPENSBI environment variable. Afterwards, compile U-Boot
+with the following commands.
+
+- For 32-bit RISC-V::
+
+    make qemu-riscv32_spl_defconfig
+    make
+
+- For 64-bit RISC-V::
+
+    make qemu-riscv64_spl_defconfig
+    make
+
+The minimal QEMU commands to run U-Boot SPL in both 32-bit and 64-bit
+configurations are:
+
+- For 32-bit RISC-V::
+
+    qemu-system-riscv32 -nographic -machine virt -bios spl/u-boot-spl \
+    -device loader,file=u-boot.itb,addr=0x80200000
+
+- For 64-bit RISC-V::
+
+    qemu-system-riscv64 -nographic -machine virt -bios spl/u-boot-spl \
+    -device loader,file=u-boot.itb,addr=0x80200000
+
+An attached disk can be emulated by adding::
+
+    -device ich9-ahci,id=ahci \
+    -drive if=none,file=riscv64.img,format=raw,id=mydisk \
+    -device ide-hd,drive=mydisk,bus=ahci.0
+
+You will have to run 'scsi scan' to use it.