The FU540-C000 is the world’s first 4+1 64-bit RISC-V SoC from SiFive. The HiFive Unleashed development platform is based on FU540-C000 and capable of running Linux.
With QEMU v4.2 or above release, the ‘sifive_u’ machine can be used to test OpenSBI image built for the real hardware as well.
To build platform specific library and firmwares, provide the PLATFORM=generic parameter to the top level make command.
The SiFive FU540 SoC platform does not have any platform-specific options.
In order to boot SMP Linux in U-Boot, Linux v5.1 (or higher) and latest U-Boot v2020.01 (or higher) should be used.
Linux Kernel Payload
The HiFive Unleashed device tree(DT) is merged in Linux v5.2 release. This DT (device tree) is not backward compatible with the DT passed from FSBL.
To use Linux v5.2 (or higher), the pre-built DTB (DT binary) from Linux v5.2 (or higher) should be used to build SiFive FU540 OpenSBI binaries by using the compile time option FW_FDT_PATH.
make PLATFORM=generic FW_PAYLOAD_PATH=<linux_build_directory>/arch/riscv/boot/Image or (For Linux v5.2 or higher) make PLATFORM=generic FW_PAYLOAD_PATH=<linux_build_directory>/arch/riscv/boot/Image FW_FDT_PATH=<hifive-unleashed-a00.dtb path from Linux kernel>
U-Boot Payload
The command-line example here assumes that U-Boot was compiled using the sifive_fu540_defconfig configuration and with U-Boot v2020.01, and up to v2021.04. sifive_unleashed_defconfig shall be used with v2021.07 or above.
make PLATFORM=generic FW_PAYLOAD_PATH=<u-boot_build_dir>/u-boot-dtb.bin
For U-Boot v2020.07-rc4 or later releases, SPL support was added in U-Boot. Please refer to the detailed U-Boot booting guide available at U-Boot.
The first stage boot loader (FSBL) expects the storage media to have a GPT partition table. It tries to look for a partition with following GUID to load the next stage boot loader (OpenSBI in this case).
2E54B353-1271-4842-806F-E436D6AF6985
That's why the generated firmware binary in above steps should be copied to the partition of the sdcard with above GUID.
dd if=build/platform/generic/firmware/fw_payload.bin of=/dev/disk2s1 bs=1024
In my case, it is the first partition is disk2s1 that has been formatted with the above specified GUID.
In case of a brand new sdcard, it should be formatted with below partition tables as described here.
sgdisk --clear \
--new=1:2048:67583 --change-name=1:bootloader --typecode=1:2E54B353-1271-4842-806F-E436D6AF6985 \
--new=2:264192: --change-name=2:root --typecode=2:0FC63DAF-8483-4772-8E79-3D69D8477DE4 \
${DISK}
Linux Kernel Payload
As Linux kernel image is embedded in the OpenSBI firmware binary, HiFive Unleashed will directly boot into Linux directly after powered on.
U-Boot Payload
As U-Boot image is used as payload, HiFive Unleashed will boot into a U-Boot prompt. U-Boot tftp boot method can be used to load kernel image in U-Boot prompt. Here are the steps do a tftpboot.
setenv ipaddr <ipaddr of the board>
setenv serverip <ipaddr of the tftp server>
setenv gatewayip <ipaddress of the network gateway>
tftpboot ${kernel_addr_r} <Image path in tftpboot directory>
tftpboot ${ramdisk_addr_r} <ramdisk path in tftpboot directory>
tftpboot ${fdt_addr_r} <hifive-unleashed-a00.dtb path in tftpboot directory>
setenv bootargs "root=<root partition> rw console=ttySIF0 earlycon=sbi"
(Note: root partition should point to ** /dev/ram ** - If a ramdisk is used ** root=/dev/mmcblk0pX ** - If a rootfs is already on some other partition of sdcard) 8. Now boot into Linux.
booti ${kernel_addr_r} ${ramdisk_addr_r} ${fdt_addr_r}
or
(If ramdisk is not loaded from network)
booti ${kernel_addr_r} - ${fdt_addr_r}
U-Boot & Linux Kernel as a single payload
At U-Boot prompt execute the following boot command to boot Linux.
booti ${kernel_addr_r} - ${fdt_addr_r}
If you want to test OpenSBI with QEMU ‘sifive_u’ machine, please follow the same instructions above, with the exception of not passing FW_FDT_PATH.
This is because QEMU generates a device tree blob on the fly based on the command line parameters, and it's compatible with the one used in the upstream Linux kernel.
When U-Boot v2021.07 (or higher) is used as the payload, as the SiFive FU540 DTB for the real hardware is embedded in U-Boot binary itself, due to the same reason above, we need to switch the U-Boot sifive_unleashed_defconfig configuration from CONFIG_OF_SEPARATE to CONFIG_OF_PRIOR_STAGE so that U-Boot uses the DTB generated by QEMU, and u-boot.bin should be used as the payload image, like:
make PLATFORM=generic FW_PAYLOAD_PATH=<u-boot_build_dir>/u-boot.bin
U-Boot v2020.07 release added SPL support to SiFive HiFive Unleashed board, hence a build error will be seen after you switch to CONFIG_OF_PRIOR_STAGE.
./tools/mkimage: Can't open arch/riscv/dts/hifive-unleashed-a00.dtb: No such file or directory ./tools/mkimage: failed to build FIT Makefile:1402: recipe for target 'u-boot.img' failed make: *** [u-boot.img] Error 1
The above errors can be safely ignored as we don't run U-Boot SPL under QEMU.
Run:
qemu-system-riscv64 -M sifive_u -m 256M -nographic \ -bios build/platform/generic/firmware/fw_payload.bin
or
qemu-system-riscv64 -M sifive_u -m 256M -nographic \ -bios build/platform/generic/firmware/fw_jump.bin \ -kernel <uboot_build_dir>/u-boot.bin
While the real hardware operates at the 64-bit mode, it's possible for QEMU to test the 32-bit OpenSBI firmware. This can be helpful for testing 32-bit SiFive specific drivers.