Architectures/ARM/Snowball

Purpose of this page

This wiki page documents the work-in-progress on making Linux, and Fedora in particular, run on the Calao Snowball board. In particular this should cover technical documentation and notes about the eMMC flashing tool, the U-boot boot loader and the Linux kernel plus device drivers.

Riff

The Snowball board contains an embedded 8GB MMC chip, or eMMC, that off-the-shelve contains several first-stage bootloader binaries, U-Boot 2009.11, and a Linaro 11.09 installation. The eMMC can be overwritten either from inside the system, or externally through a USB cable using the Riff tool.

Compilation is a bit painful by default, because the tool is abandoned and designed with a different distro in mind. Specific problems include expectations on the filenames for Xalan-j2, a seemingly non-working install make target and poor instructions in the README files.

Todo
- Document how to build Riff for Fedora - Provide a spec-file and/or RPM for Riff

U-Boot

U-boot is situated on the eMMC at offset 0x120000. Riff can be used to write a new build of the bootloader to this address. The size of U-boot is stored in a 4-byte integer at 0x200a4. Upstream U-Boot can be used on the Snowball board, but loading a kernel from the eMMC does not work due to a regression introduced in:

e95504497ecac46907204b0ee3460b708a2981ac mmc: Split device init to decouple OCR-polling delay

Reverting this commit makes U-boot work. By default the upstream U-boot has no support for Device Tree or network boot. The latter is supported by the preloaded image.

Todo - upstream work
- Fix the above commit for Snowball

- Enable FDT support in U-boot for Snowball

- Enable networking support in U-boot for Snowball