This adds detailed documentation for RISC-V `sifive_u` machine, including the following information: - Supported devices - Hardware configuration information - Boot options - Machine-specific options - Running Linux kernel - Running VxWorks kernel - Running U-Boot, and with an alternate configuration Signed-off-by: Bin Meng <bin.meng@windriver.com> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Message-id: 20210126060007.12904-10-bmeng.cn@gmail.com Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
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337 lines
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SiFive HiFive Unleashed (``sifive_u``)
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======================================
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SiFive HiFive Unleashed Development Board is the ultimate RISC-V development
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board featuring the Freedom U540 multi-core RISC-V processor.
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Supported devices
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-----------------
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The ``sifive_u`` machine supports the following devices:
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* 1 E51 / E31 core
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* Up to 4 U54 / U34 cores
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* Core Level Interruptor (CLINT)
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* Platform-Level Interrupt Controller (PLIC)
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* Power, Reset, Clock, Interrupt (PRCI)
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* L2 Loosely Integrated Memory (L2-LIM)
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* DDR memory controller
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* 2 UARTs
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* 1 GEM Ethernet controller
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* 1 GPIO controller
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* 1 One-Time Programmable (OTP) memory with stored serial number
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* 1 DMA controller
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* 2 QSPI controllers
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* 1 ISSI 25WP256 flash
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* 1 SD card in SPI mode
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Please note the real world HiFive Unleashed board has a fixed configuration of
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1 E51 core and 4 U54 core combination and the RISC-V core boots in 64-bit mode.
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With QEMU, one can create a machine with 1 E51 core and up to 4 U54 cores. It
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is also possible to create a 32-bit variant with the same peripherals except
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that the RISC-V cores are replaced by the 32-bit ones (E31 and U34), to help
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testing of 32-bit guest software.
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Hardware configuration information
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----------------------------------
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The ``sifive_u`` machine automatically generates a device tree blob ("dtb")
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which it passes to the guest. This provides information about the addresses,
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interrupt lines and other configuration of the various devices in the system.
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Guest software should discover the devices that are present in the generated
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DTB instead of using a DTB for the real hardware, as some of the devices are
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not modeled by QEMU and trying to access these devices may cause unexpected
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behavior.
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Boot options
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------------
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The ``sifive_u`` machine can start using the standard -kernel functionality
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for loading a Linux kernel, a VxWorks kernel, a modified U-Boot bootloader
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(S-mode) or ELF executable with the default OpenSBI firmware image as the
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-bios. It also supports booting the unmodified U-Boot bootloader using the
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standard -bios functionality.
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Machine-specific options
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------------------------
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The following machine-specific options are supported:
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- serial=nnn
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The board serial number. When not given, the default serial number 1 is used.
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SiFive reserves the first 1 KiB of the 16 KiB OTP memory for internal use.
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The current usage is only used to store the serial number of the board at
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offset 0xfc. U-Boot reads the serial number from the OTP memory, and uses
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it to generate a unique MAC address to be programmed to the on-chip GEM
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Ethernet controller. When multiple QEMU ``sifive_u`` machines are created
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and connected to the same subnet, they all have the same MAC address hence
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it creates an unusable network. In such scenario, user should give different
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values to serial= when creating different ``sifive_u`` machines.
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- start-in-flash
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When given, QEMU's ROM codes jump to QSPI memory-mapped flash directly.
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Otherwise QEMU will jump to DRAM or L2LIM depending on the msel= value.
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When not given, it defaults to direct DRAM booting.
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- msel=[6|11]
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Mode Select (MSEL[3:0]) pins value, used to control where to boot from.
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The FU540 SoC supports booting from several sources, which are controlled
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using the Mode Select pins on the chip. Typically, the boot process runs
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through several stages before it begins execution of user-provided programs.
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These stages typically include the following:
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1. Zeroth Stage Boot Loader (ZSBL), which is contained in an on-chip mask
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ROM and provided by QEMU. Note QEMU implemented ROM codes are not the
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same as what is programmed in the hardware. The QEMU one is a simplified
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version, but it provides the same functionality as the hardware.
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2. First Stage Boot Loader (FSBL), which brings up PLLs and DDR memory.
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This is U-Boot SPL.
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3. Second Stage Boot Loader (SSBL), which further initializes additional
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peripherals as needed. This is U-Boot proper combined with an OpenSBI
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fw_dynamic firmware image.
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msel=6 means FSBL and SSBL are both on the QSPI flash. msel=11 means FSBL
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and SSBL are both on the SD card.
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Running Linux kernel
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--------------------
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Linux mainline v5.10 release is tested at the time of writing. To build a
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Linux mainline kernel that can be booted by the ``sifive_u`` machine in
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64-bit mode, simply configure the kernel using the defconfig configuration:
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.. code-block:: bash
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$ export ARCH=riscv
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$ export CROSS_COMPILE=riscv64-linux-
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$ make defconfig
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$ make
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To boot the newly built Linux kernel in QEMU with the ``sifive_u`` machine:
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.. code-block:: bash
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$ qemu-system-riscv64 -M sifive_u -smp 5 -m 2G \
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-display none -serial stdio \
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-kernel arch/riscv/boot/Image \
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-initrd /path/to/rootfs.ext4 \
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-append "root=/dev/ram"
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To build a Linux mainline kernel that can be booted by the ``sifive_u`` machine
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in 32-bit mode, use the rv32_defconfig configuration. A patch is required to
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fix the 32-bit boot issue for Linux kernel v5.10.
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.. code-block:: bash
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$ export ARCH=riscv
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$ export CROSS_COMPILE=riscv64-linux-
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$ curl https://patchwork.kernel.org/project/linux-riscv/patch/20201219001356.2887782-1-atish.patra@wdc.com/mbox/ > riscv.patch
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$ git am riscv.patch
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$ make rv32_defconfig
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$ make
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Replace ``qemu-system-riscv64`` with ``qemu-system-riscv32`` in the command
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line above to boot the 32-bit Linux kernel. A rootfs image containing 32-bit
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applications shall be used in order for kernel to boot to user space.
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Running VxWorks kernel
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----------------------
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VxWorks 7 SR0650 release is tested at the time of writing. To build a 64-bit
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VxWorks mainline kernel that can be booted by the ``sifive_u`` machine, simply
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create a VxWorks source build project based on the sifive_generic BSP, and a
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VxWorks image project to generate the bootable VxWorks image, by following the
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BSP documentation instructions.
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A pre-built 64-bit VxWorks 7 image for HiFive Unleashed board is available as
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part of the VxWorks SDK for testing as well. Instructions to download the SDK:
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.. code-block:: bash
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$ wget https://labs.windriver.com/downloads/wrsdk-vxworks7-sifive-hifive-1.01.tar.bz2
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$ tar xvf wrsdk-vxworks7-sifive-hifive-1.01.tar.bz2
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$ ls bsps/sifive_generic_1_0_0_0/uboot/uVxWorks
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To boot the VxWorks kernel in QEMU with the ``sifive_u`` machine, use:
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.. code-block:: bash
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$ qemu-system-riscv64 -M sifive_u -smp 5 -m 2G \
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-display none -serial stdio \
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-nic tap,ifname=tap0,script=no,downscript=no \
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-kernel /path/to/vxWorks \
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-append "gem(0,0)host:vxWorks h=192.168.200.1 e=192.168.200.2:ffffff00 u=target pw=vxTarget f=0x01"
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It is also possible to test 32-bit VxWorks on the ``sifive_u`` machine. Create
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a 32-bit project to build the 32-bit VxWorks image, and use exact the same
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command line options with ``qemu-system-riscv32``.
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Running U-Boot
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--------------
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U-Boot mainline v2021.01 release is tested at the time of writing. To build a
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U-Boot mainline bootloader that can be booted by the ``sifive_u`` machine, use
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the sifive_fu540_defconfig with similar commands as described above for Linux:
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.. code-block:: bash
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$ export CROSS_COMPILE=riscv64-linux-
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$ export OPENSBI=/path/to/opensbi-riscv64-generic-fw_dynamic.bin
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$ make sifive_fu540_defconfig
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You will get spl/u-boot-spl.bin and u-boot.itb file in the build tree.
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To start U-Boot using the ``sifive_u`` machine, prepare an SPI flash image, or
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SD card image that is properly partitioned and populated with correct contents.
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genimage_ can be used to generate these images.
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A sample configuration file for a 128 MiB SD card image is:
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.. code-block:: bash
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$ cat genimage_sdcard.cfg
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image sdcard.img {
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size = 128M
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hdimage {
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gpt = true
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}
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partition u-boot-spl {
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image = "u-boot-spl.bin"
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offset = 17K
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partition-type-uuid = 5B193300-FC78-40CD-8002-E86C45580B47
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}
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partition u-boot {
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image = "u-boot.itb"
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offset = 1041K
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partition-type-uuid = 2E54B353-1271-4842-806F-E436D6AF6985
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}
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}
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SPI flash image has slightly different partition offsets, and the size has to
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be 32 MiB to match the ISSI 25WP256 flash on the real board:
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.. code-block:: bash
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$ cat genimage_spi-nor.cfg
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image spi-nor.img {
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size = 32M
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hdimage {
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gpt = true
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}
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partition u-boot-spl {
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image = "u-boot-spl.bin"
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offset = 20K
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partition-type-uuid = 5B193300-FC78-40CD-8002-E86C45580B47
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}
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partition u-boot {
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image = "u-boot.itb"
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offset = 1044K
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partition-type-uuid = 2E54B353-1271-4842-806F-E436D6AF6985
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}
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}
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Assume U-Boot binaries are put in the same directory as the config file,
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we can generate the image by:
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.. code-block:: bash
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$ genimage --config genimage_<boot_src>.cfg --inputpath .
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Boot U-Boot from SD card, by specifying msel=11 and pass the SD card image
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to QEMU ``sifive_u`` machine:
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.. code-block:: bash
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$ qemu-system-riscv64 -M sifive_u,msel=11 -smp 5 -m 8G \
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-display none -serial stdio \
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-bios /path/to/u-boot-spl.bin \
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-drive file=/path/to/sdcard.img,if=sd
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Changing msel= value to 6, allows booting U-Boot from the SPI flash:
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.. code-block:: bash
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$ qemu-system-riscv64 -M sifive_u,msel=6 -smp 5 -m 8G \
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-display none -serial stdio \
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-bios /path/to/u-boot-spl.bin \
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-drive file=/path/to/spi-nor.img,if=mtd
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Note when testing U-Boot, QEMU automatically generated device tree blob is
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not used because U-Boot itself embeds device tree blobs for U-Boot SPL and
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U-Boot proper. Hence the number of cores and size of memory have to match
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the real hardware, ie: 5 cores (-smp 5) and 8 GiB memory (-m 8G).
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Above use case is to run upstream U-Boot for the SiFive HiFive Unleashed
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board on QEMU ``sifive_u`` machine out of the box. This allows users to
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develop and test the recommended RISC-V boot flow with a real world use
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case: ZSBL (in QEMU) loads U-Boot SPL from SD card or SPI flash to L2LIM,
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then U-Boot SPL loads the combined payload image of OpenSBI fw_dynamic
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firmware and U-Boot proper. However sometimes we want to have a quick test
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of booting U-Boot on QEMU without the needs of preparing the SPI flash or
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SD card images, an alternate way can be used, which is to create a U-Boot
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S-mode image by modifying the configuration of U-Boot:
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.. code-block:: bash
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$ make menuconfig
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then manually select the following configuration in U-Boot:
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Device Tree Control > Provider of DTB for DT Control > Prior Stage bootloader DTB
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This lets U-Boot to use the QEMU generated device tree blob. During the build,
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a build error will be seen below:
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.. code-block:: none
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MKIMAGE u-boot.img
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./tools/mkimage: Can't open arch/riscv/dts/hifive-unleashed-a00.dtb: No such file or directory
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./tools/mkimage: failed to build FIT
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make: *** [Makefile:1440: u-boot.img] Error 1
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The above errors can be safely ignored as we don't run U-Boot SPL under QEMU
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in this alternate configuration.
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Boot the 64-bit U-Boot S-mode image directly:
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.. code-block:: bash
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$ qemu-system-riscv64 -M sifive_u -smp 5 -m 2G \
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-display none -serial stdio \
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-kernel /path/to/u-boot.bin
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It's possible to create a 32-bit U-Boot S-mode image as well.
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.. code-block:: bash
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$ export CROSS_COMPILE=riscv64-linux-
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$ make sifive_fu540_defconfig
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$ make menuconfig
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then manually update the following configuration in U-Boot:
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Device Tree Control > Provider of DTB for DT Control > Prior Stage bootloader DTB
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RISC-V architecture > Base ISA > RV32I
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Boot images > Text Base > 0x80400000
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Use the same command line options to boot the 32-bit U-Boot S-mode image:
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.. code-block:: bash
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$ qemu-system-riscv32 -M sifive_u -smp 5 -m 2G \
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-display none -serial stdio \
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-kernel /path/to/u-boot.bin
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.. _genimage: https://github.com/pengutronix/genimage
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