Boot from specific partition using sd card - RCAR M06 KF Board

Hello everyone.

I hope everyone is doing well; I have one scenario for updating the device firmware.'


I have three partitions:
NO. 1 PARTITION - Boot folder (contains image and r8a7795-h3ulcb-4x2g-kf.dtb)

PART 2: Rootfs

PARTITION 3 - Empty partition - This is where the new rootfs will be unzipped/untarred.

During boot, I want to check partition 3 to read explicitly for rootfs, and if none is found, I want to check partition 2 for rootfs.

I've set the following u-boot parameters:

bootargs_emmc2='rw root=/dev/mmcblk1p2 rootdelay=5'
bootargs_emmc3='rw root=/dev/mmcblk1p3 rootdelay=5'
setenv bootargs "${bootargs_emmc2}; ${bootargs_emmc3}"
setenv bootcmd "ext2load mmc 0:1 0x48080000 /boot/Image; ext2load mmc 0:1 0x48000000 /boot/r8a7795-h3ulcb-4x2g-kf.dtb; booti 0x48080000 - 0x48000000"
saveenv

I followed the instructions at elinux.org/.../.
I'm getting the following error: devtmpfs: mounting error -2 (may be uboot not able to find rootfs but it is not fallback to read partition 2).

When I explicitly set bootargs to emmc2, the board boots up normally.

My question is whether there is a way to force uboot to read rootfs from part#3 if part#3 is not present, and to read rootfs from part#2 if part#3 is not present.

Any help will be appreciated Slight smile