Report on Chrome OS upstreaming

In the last months there was lots of activity in the coreboot repository due to upstreaming the work that was done in Chrome OS’ branch. We’re happy to announce that both code bases are again relatively close to each other.

In the last 7 months, about 1500 commits that landed in coreboot originated in Chrome OS’ repository (of about 2600 total). Those came from 20 domains, which represent pretty much every part of the coreboot community: well known private and commercial coreboot contributors, but also BIOS and silicon developers as well as device manufacturers.

As a result, upstream benefits from lots of new features and hardware support that was introduced during Chrome OS development, some of which warrant a shout out:

First, new hardware support: There’s MIPS support, and on the ARM side we now run on SoCs by Broadcom, Marvell, Qualcomm, and RockChip.

In terms of infrastructure, the biggest single item that came up during upstreaming is probably a safe method to declare the memory map on devices. Compared to x86, most architectures that prospered in embedded applications have a more complicated view on memory, so more care is required there.

Looking at files like src/soc/nvidia/tegra132/include/soc/memlayout.ld, it becomes clear what kind of memory is available for which purpose on that SoC.

In addition to that, there are efforts to make Chrome OS’ verified boot available as an option in upstream coreboot, and also to update the flash image format to allow for safer incremental updates.

One thing to note is that significant contributions that went into the tree recently were written with active support by Broadcom, Imagination Technologies, Intel, Marvell, Nvidia, Qualcomm, and RockChip. Welcome to coreboot!

In the future, Chrome OS will move over to a new branch point from upstream, and work on strategies to avoid diverging for two long years again. Instead, we’re looking for ways to keep the trees closer while also avoiding flooding the coreboot.org developer base with hundreds of patches. More on that as it is implemented.

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