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bf3c641e97
Rework the boot state machine to a significantly simpler and more robust implementation. The basic idea is to revert to the previous partition whenever an issue is detected during the boot process. - Broken SPL If one of the two SPLs does not boot, the ROM code of the i.MX8 SoC automatically starts the second SPL from the second boot partition. For example, if the system's active partition is A but the SPL from partition A is broken, the ROM code automatically uses the SPL/u-boot from partition B. Proceeding with this boot procedure would lead to booting the kernel/ rootfs from partition A, which could potentially successfully boot the system and allow the user to apply the firmware update with the broken SPL again. This would lead to a non-bootable system because the second update would overwrite the last working bootloader. To prevent such situations, zigzag boots are detected and the system reverts to the previous partition rather than booting the kernel/rootfs from the currently active partition. Detecting zigzag boots is done via the new fallback variable. To make this state machine even more consistent, the partitionset_active variable is no longer used to determine the active partition during boot. Instead, the active partition is always read from the eMMC partconf registers. For backward compatibility, the partitionset_active variable is still updated whenever a partition switch occurs. However, u-boot no longer relies on this variable, as it could potentially be out of sync with the actual partition state, leading to situations where the ROM code of the i.MX8 SoC would be out of sync with u-boot. - Broken kernel, initramfs or rootfs If the upgrade_available variable is set, u-boot counts the number of consecutive boots via the bootcount variable. If the bootcount exceeds the bootlimit variable, u-boot starts the altbootcmd instead of the bootcmd. Previously, this logic was bypassed by assigning the regular bootcmd to altbootcmd. Now, the altbootcmd is used to revert to the previous partition when the bootlimit is exceeded. The netdev variable is changed to eth0 by default. This is what the FEC driver uses on Capricorn boards. For devices with switches and DSA subsystems in use, the netdev should be set accordingly by additional logic in the environment or u-boot code. This is not part of this commit. Signed-off-by: Adrian Freihofer <adrian.freihofer@siemens.com> Signed-off-by: Heiko Schocher <hs@nabladev.com> Reviewed-by: Peng Fan <peng.fan@nxp.com>