diff options
Diffstat (limited to 'docs/firmware/payload_uboot.md')
| -rw-r--r-- | docs/firmware/payload_uboot.md | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/docs/firmware/payload_uboot.md b/docs/firmware/payload_uboot.md new file mode 100644 index 0000000..3fd7fa2 --- /dev/null +++ b/docs/firmware/payload_uboot.md @@ -0,0 +1,38 @@ +U-Boot as a payload to OpenSBI +============================== + +[U-Boot](https://www.denx.de/wiki/U-Boot) is an open-source primary boot loader. +It can be used as first and/or second stage boot loader in an embedded +environment. In the context of OpenSBI, U-boot can be specified as a payload to +OpenSBI firmware, becoming the boot stage following OpenSBI firmware +execution. + +The current stable upstream code of U-boot does not yet include all patches +necessary to fully support OpenSBI. To use U-Boot as an OpenSBI payload, the +following out-of-tree patch series must be applied to the upstream U-Boot source +code. + +HiFive Unleashed support for U-Boot + +https://lists.denx.de/pipermail/u-boot/2019-February/358058.html + +This patch series enables a single CPU to execute U-Boot. As a result, the next +stage boot code such as Linux kernel can also only execute a single CPU. U-Boot +SMP support for RISC-V can be enabled with the following additional patches. + +https://lists.denx.de/pipermail/u-boot/2019-February/358393.html + +Building and Generating U-Boot images +===================================== +Please refer to U-Boot build documentation for detailed instructions on how to build U-Boot images. + +Once U-Boot images are built, Linux kernel image need to be converted to a format +that U-Boot understands. + +``` +<uboot-dir>/tools/mkimage -A riscv -O linux -T kernel -C none -a 0x80200000 -e 0x80200000 -n Linux -d \ + <linux_build_directory>arch/riscv/boot/Image \ + <linux_build_directory>/arch/riscv/boot/uImage +``` + +Copy the uImage to your tftpboot server path if network boot is required. |