[PATCH v2 0/4] Add support for Chromium OS and Google WiFi

[Paul Spooren]

On Sat Jan 16, 2021 at 5:07 PM HST, Brian Norris wrote:
> Hi,
>
> This series adds support for both Chromium OS (or particularly, its
> kernel-payload signing and disk layout) and for a device using it (the
> first generation Google WiFi).
>
> Google WiFi (code-named "Gale") is an IPQ4019-based AP. Its hardware is
> decently supported by the existing ipq40xx target -- see patch 4 for
> more notes. Notably missing: reboot does not work properly -- I have
> some separate TrustZone/SCM-related patches I'd like to clean up to
> enable this later.
>
> I sent v1 as an "RFC" here:
> http://patchwork.ozlabs.org/project/openwrt/patch/20200718205148.1743807-6-computersforpeace@gmail.com/
> and since I got only mechanical feedback for the last patch, I'm now
> sending a non-RFC. I leave some notes about my implementation choices
> below, for reference.
>
> Changes since v1:
> * 1 patch was already merged
> * patch 4 is rebased, improved (see patch 4 for notes)
>
> Chromium OS (the open-source OS on which Google builds its Chrome OS) --
> "CrOS" for short -- typically boots via Coreboot, plus Depthcharge as a
> second stage. Such bootloaders utilize a verified boot toolkit [1] to
> verify each subsequent stage. Of note:
>
> 1. The kernel should be placed in a GPT partition with a custom "Chrome
> OS kernel" GUID type and a few custom flags (to manage the A/B
> OS updates employed by Chromium OS). CrOS vboot provides the `cgpt`
> utility for creating and managing such partitions.
> 2. That partition should hold a vboot payload, signed and packaged per
> the format documented and implemented at [1]. Using the vboot
> utilities, this involves the `vbutil_kernel --pack ...` command.
>
> I chose:
>
> (a) To extend OpenWRT's ptgen to help customize partition types,
> instead of packaging vboot's `cgpt`.
> (b) To adapt and reimplement the `vbutil_kernel` command as a custom
> `cros-vbutil` utility, rather than packaging Google's utility.
> (c) To add kernel and rootfs partition-size parameters (for customizing
> my GPT), but it's not clear to me if this fits well into the
> existing ipq40xx target, or if it should be done differently.
>
> For some alternatives (especially on (b)), I did package
> futility/vbutil_kernel here:
> https://github.com/openwrt/packages/pull/12829
> I could adapt this into tools/ instead, so OpenWRT doesn't have to carry
> my re-implementation. This would carry some extra build complexity,
> as the vboot tools are >10,000 lines of code, compared to my
> reimplementation of a few hundred lines. The library dependencies are
> similar (mostly just crypto/ssl, and potentially libuuid (for GPT)), as
> the vboot project tries to keep the code semi-portable / reusable.
>
> Packaging the vboot utilities might give us some future flexibility, if
> the formats grow and change for future systems. So far, I think the
> format has been pretty stable. Also, there are potentially some quirks I
> missed in my port related the ${ARCH} -- I ported the ARM support, but
> there may be some small tweaks I missed that are applicable only to x86
> systems.
>
> For (c): adding this to the common ipq40xx target means that there will
> be a new CONFIG_TARGET_KERNEL_PARTSIZE and
> CONFIG_TARGET_ROOTFS_PARTSIZE, which are only applicable to a single
> device but are present for all:
> FEATURES:=boot-part rootfs-part
>
> Regards,
> Brian
>
> [1]
> https://chromium.googlesource.com/chromiumos/platform/vboot_reference
>
> Brian Norris (4):
> firmware-utils/ptgen: add Chromium OS kernel partition support
> firmware-utils/cros-vbutil: add Chrome OS vboot kernel-signing utility
> image-commands: support Chromium OS image-type creation
> ipq40xx: add target for Google WiFi (Gale)

I rebased the last patch onto 378c7ff282101b204d2a29fa080ed66f2a14940d
and fixed a typo which would break the vboot script. Changed are pushed
to my staging tree[2], let's see if my "staging" buildbots[3] like the
patch.

Thanks for your work!

[2]: https://git.openwrt.org/?p=openwrt/staging/aparcar.git;a=summary
[3]: https://buildmaster.aparcar.org/master/phase1/#/builders/56

>
> include/image-commands.mk | 18 +
> .../base-files/files/lib/upgrade/common.sh | 4 +-
> scripts/gen_image_vboot.sh | 36 ++
> target/linux/ipq40xx/Makefile | 2 +-
> .../ipq40xx/base-files/etc/board.d/02_network | 1 +
> .../base-files/lib/upgrade/platform.sh | 16 +
> .../arch/arm/boot/dts/qcom-ipq4019-wifi.dts | 402 ++++++++++++
> target/linux/ipq40xx/image/Makefile | 13 +
> .../901-arm-boot-add-dts-files.patch | 3 +-
> tools/firmware-utils/Makefile | 1 +
> tools/firmware-utils/src/cros-vbutil.c | 609 ++++++++++++++++++
> tools/firmware-utils/src/ptgen.c | 39 +-
> 12 files changed, 1138 insertions(+), 6 deletions(-)
> create mode 100755 scripts/gen_image_vboot.sh
> create mode 100644
> target/linux/ipq40xx/files/arch/arm/boot/dts/qcom-ipq4019-wifi.dts
> create mode 100644 tools/firmware-utils/src/cros-vbutil.c
>
> --
> 2.29.2
>
>
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