chainloading LOS prebuild image

[99degree]

currently cant chain loading prebuild image.

Here are some suggestion for fastboot boot cmd:
(1)Since dtb is split into boot and dtbo so we have to combine back to one. will provide detail soon.
(2)Proved bootloader is having avb/encryption by design and depending on unmodified boot partition.
so in order to get rid of it, u-boot img need to get flash into ufs boot partition first (of course backup user data first).
then go to recovery to clean up cache/data partition. bootloader had assumed fastboot boot cmd is non-secured, so if the signature/checksum is not same to boot partition then it wont enable crypto engine and resulting boot into android cause error and reboot.
(3)after above preparation, boot into uboot is fine and chainload by fastboot boot is doing fine.

[99degree]

check below on how to get a new boot.img:

#5

[99degree]

download the uboot binary for test:
https://github.com/99degree/u-boot/actions/runs/14388533585

[99degree]

ok now bootflow cmd is hacked to replicated the fastboot boot logic so there is no more blocking issue to just chainload LOS

[99degree]

Here is a recommended step to play with u-boot chainloading LOS miatoll:
(1) download u-boot binary for miatoll. https://github.com/99degree/u-boot/actions/workflows/build-images.yml
(2) plug in los device to host, download fdt by #5
(3) prepare boot.img, test it make sure it works
(4) backup all apps and settings of LOS
(4) flash u-boot into ufs boot partition
(5) reboot to recovery by vol-down reboot or adb reboot recovery
(6) in recovery, wipe all data/cache
(7) in bootloader, fastboot erase dtbo
(8) make sure a plugin mmc card have partitioned with at least with 2, one should be named boot, in first 4 partition within , other might and EFI esp etc. will create a new issue to show an example. #6
(9) reboot and enter u-boot. test the new_boot.img by fastboot boot new_boot.img
(10) if anything are smooth, enter u-boot again. do fastboot flash boot new_boot.img
(11) "fastboot continue" to enter boot menu for any reboot. or wait for 120s to let fastboot time-out.
(12) in boot menu select boot, bootflow will search available boot option and show as a menu. my have android as boot partition and postmarketOS/AOSP as alternative. you might flash AOSP in mmc with similar approach but is not within scope.
(13) select android as boot item, vola, enter LOS with full function except USB. chainload is done!

[99degree]

a rough tutorial for prepare aosp img for miatoll is at https://github.com/99degree/linux/wiki/AOSP-image-for-miatoll