While porting Freedesktop SDK to the EBC7700 for my FOSDEM'26 talk [1], I encountered some UEFI boot issues, which motivated me to dig deeper and uncover all the mysteries about the RISC-V boot chain. This talk looks in-depth at the RISC-V boot chain, both on the virtualised QEMU target, as well as practical hardware examples. Starting from their boot ROMs and how fusing/strapping may select the boot sources, usually containing some form of an SPL, like the one from U-Boot. Such SPL, in turn, loads U-Boot proper, which contains OpenSBI, implementing the Supervisor Binary Interface, in so-called FW_DYNAMIC form, meaning it does not require any platform-specific configuration parameters because all required information is passed by the previous booting stage at runtime. OpenSBI gets executed first and stays resident. The handover to the U-Boot boot loader, which implements the UEFI specification, marks the next boot stage. It may either directly load the Linux kernel, an optional initial RAM disk and the device tree, particularly useful during bring-up/development, or launch a UEFI boot loader like systemd-boot or GRUB. Handover to the Linux kernel marks the last and final stage in the boot chain. This talk not only looks at the software involved, but also how it may be built, deployed and debugged. As usual, I complete my talk with a live demo.

[1] https://fosdem.org/2026/schedule/event/LX3NNU-upstream-embedded-linux-on-risc-v-sbcs