Re: [yocto] [meta-rockchip][PATCH v4 4/5] remove /boot partition

[Trevor Woerner <twoerner@gmail.com>]

On Thu 2024-02-22 @ 12:04:14 PM, Trevor Woerner via lists.yoctoproject.org wrote:
> In order to boot successfully, most Rockchip SoCs require a specific
> partitioning scheme which was defined many years (and many SoCs) ago. That
> partitioning scheme places the SPL and U-Boot at specific offsets at the
> start of the boot block device:
> 
>         https://opensource.rock-chips.com/wiki_Partitions
> 
> The Rockchip partitioning scheme goes on to also define the locations
> of a number of additional partitions, including the "boot" and "root"
> partitions.
> 
> Since both the SPL and U-Boot have already been placed on the block device,
> the "boot" partition only contains the extlinux config file and the
> kernel+dtb/fitImage; it doesn't contain any bootloader artifacts (other
> than the extlinux config).
> 
> The location of the SPL partition is a hard dependency since the BOOTROM
> etched inside the Rockchip SoCs is programmed to load and run a validated
> binary it finds at this location. The locations of the "boot" and "root"
> partitions are not so rigid since it is U-Boot which interacts with them.
> U-Boot is very flexible with how it finds boot components, and in its
> support for various devices, filesystems, sizes, etc.
> 
> Both oe-core's U-Boot metadata and wic's bootimg-partition script contain
> logic to generate the extlinux pieces required for a bootloader to boot
> a Linux system. If both are enabled, the wic pieces silently clobber the
> U-Boot pieces. However, the mechanisms contained in the U-Boot metadata are
> much more flexible, from a user's point of view, than the mechanisms in
> wic's bootimg-partition.
> 
> If a user wishes to setup some sort of A/B redundant update mechanism, they
> must have redundant root partitions (in order to update their filesystem
> contents) but they also need to have redundant boot partitions if they
> wish to update the kernel as part of their update mechanism. Pairing
> redundant kernel partitions with redundant filesystem partitions becomes
> unnecessarily complicated. Therefore it makes sense to combine the kernel
> and the filesystem into the same partition so that both the kernel and
> filesystem are updated, or rolled back, in lock-step as one unit. Specific
> kernel versions and configurations often have dependencies on user-space
> components and versions.
> 
> The /boot location is not going away. This patch simply transfers
> responsibility for its creation to the more flexible U-Boot mechanism
> and includes the kernel as part of the same partition as the root
> filesystem. Not only does it add flexibility, it also makes update schemes
> more straightforward. Although having a separate /boot partition is a
> "requirement" of the Rockchip partitioning scheme, it is not an actual
> hard requirement when using a flexible, open-source bootloader (such as
> U-Boot) instead of using Rockchip's proprietary miniloader, preloader, and
> trust.img.
> 
> Build-tested for all boards.
> Run-tested on:
> 	nanopi-m4-2gb, nanopi-m4b, nanopi-r2s, nanopi-r4s, roc-rk3328-cc,
> 	rock-3a, rock-5a, rock-5b, rock-pi-4b, rock-pi-e, rock-pi-s,
> 	rock64
> 
> Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
> Signed-off-by: Trevor Woerner <twoerner@gmail.com>
> ---
> changes in v4:
> - updated for latest rockchip.wks
> - remove offset for /boot partition (let wic calculate this)
> 
> changes in v3:
> - add back the comment explaining the need for NONFITDT
> - change the inclusion of the u-boot-extlinux package from RRECOMMENDS
>   to RDEPENDS
> - clarify the commit message to remove the un-true statement that sizes
>   are hard requirements
> - add back the "--ptable gpt" line to rockchip.wks
> 
> changes in v2:
> - add UBOOT_EXTLINUX_FDT and tweak UBOOT_EXTLINUX_FDTDIR to modify their
>   behaviour based on whether or not KERNEL_IMAGETYPE is fitImage
> - remove extraneous WKS_FILE_DEPENDS
> - remove "--ptable gpt" from wks
> - move newly added "earlycon" to UBOOT_EXTLINUX_CONSOLE
> - re-word the commit message to better explain the behaviour of the
>   Rockchip BootROM
> ---
>  conf/machine/include/rockchip-defaults.inc |  2 ++
>  conf/machine/include/rockchip-extlinux.inc | 24 ++++++++++++++++++++++
>  conf/machine/include/rockchip-wic.inc      | 20 ++----------------
>  wic/rockchip.wks                           | 12 +++++------
>  4 files changed, 33 insertions(+), 25 deletions(-)
>  create mode 100644 conf/machine/include/rockchip-extlinux.inc

Applied to meta-rockchip, master branch.