Merge tag 'efi-2024-10-rc1-3' of https://source.denx.de/u-boot/custodians/u-boot-efi

Pull request efi-2024-10-rc1-3

Documentation:

* Move out-of-tree building info to HTML
* Enable ReadTheDocs addon management
* Remove FIT documentation that is elsewhere
* Update table of contents for FIT images
* Add description for more boot methods

UEFI:

* Correct finding distro device-path for media devices
* Fix typo in EFI_RT_VOLATILE_STORE description

Other:

* MAINTAINERS: Rename BOOTDEVICE

1 files changed, 33 insertions, 0 deletions

diff --git a/doc/develop/bootstd/cros.rst b/doc/develop/bootstd/cros.rst
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+.. SPDX-License-Identifier: GPL-2.0+:
+
+ChromiumOS Bootmeth
+===================
+
+ChromiumOS provides a mechanism for booting its Operating System from a block
+device, described
+`here <https://www.chromium.org/chromium-os/chromiumos-design-docs/verified-boot/>`_.
+
+U-Boot includes support for reading the associated data structures from the
+device and identifying a bootable ChromiumOS image. This structure includes the
+kernel itself, boot arguments (kernel command line), as well as the x86 setup
+block (for x86 only).
+
+When invoked on a bootdev, this bootmeth searches for kernel partitions with
+the appropriate GUID (Globally Unique Identifier). When found, the information
+is loaded and a bootflow is created.
+
+When the bootflow is booted, the bootmeth reads the kernel and boot arguments.
+It then boots the kernel using zboot (on x86) or bootm (on ARM). The boot
+arguments are adjusted to replace `%U` with the UUID of the selected kernel
+partition. This results in the correct root disk being used, which is the next
+partition after the kernel partition.
+
+For ARM, a :doc:`/usage/fit/index` is used. The `CONFIG_FIT_BEST_MATCH` option
+must be enabled for U-Boot to select the correct devicetree to boot with.
+
+Note that a ChromiumOS image typically has two copies of the Operating System,
+each with its own kernel and root disk. There is no initial ramdisk (initrd).
+This means that this bootmeth typically locates two separate images.
+
+The compatible string "u-boot,cros" is used for the driver. It is present
+if `CONFIG_BOOTMETH_CROS` is enabled.