I started building the firmware components for booting the BPI-F3 myself. While SpacemiT provides the source code of the different components the official firmware is built from forks of older versions and without the commit history. In my attempt to build a custom firmware I will use mainline versions where possible and otherwise create my own forks from mainline sources and merge necessary changes into it.

Contents:

Status#

name	build	test	comment
bootinfo	✅	✅	generated files are identical to vendor files
fsbl	❌	❌	no build yet
opensbi	✅	✅	boot ok (opensbi messages shown in console)
u-boot	✅	❌	doesn’t boot linux and only detects 4GB RAM

Bootinfo#

The first part of the boot process we have control of is the bootinfo binary. In the SpacemiT BSP Bianbu Linux the bootinfo is generated by a Python script during the build of u-boot.

With bpif3_gen_binary I extracted and slightly modified this script and according configuration files to be used independent from the u-boot source tree.

The content of the generated bootinfo is specified in a JSON file and could be modified. However, currently I do not see a need for that.

FSBL (U-Boot SPL)#

The FSBL (First Stage Boot Loader) is generated by the same script as the bootinfo but requires u-boot-spl.bin at a path specified in the according JSON configuration file.

While mainline u-boot already has support for the BPI-F3, it only generates a u-boot proper stage but not a u-boot spl stage.

OpenSBI#

Mainline OpenSBI does not have support for the SpacemiT K1 (yet). Luckily cyyself already merged support for the SoC into a clean fork of OpenSBI.

With bpif3_opensbi I merged his work on to the latest version of mainline OpenSBI.

U-Boot#

Mainline u-boot has support for the BPI-F3. It lacks support for the u-boot spl stage but builds the u-boot proper main stage.