extlinux.conf on production modules (eMMC) always has priority over other drives

[careyer]

Hey there! Many thanks for this awesome work! I played arround with it on my Jetson TX2 NX production model (eMMC).

Describe the issue
Is there a way to specify a boot fallback strategy in /boot/extlinux/extlinux.conf for production modules?

On the production modules with integrated eMMC for the sake of it the system first looks into extlinux.conf on /dev/mmcblk0p1/ before it looks e.g. into extlinux.conf on /dev/sdb1.
I.e. mmcblk0p1 (which cannot be unplugged due to being soldered eMMC) has always priority over the other drives resulting in the fact that you must edit the extlinux.conf in eMMC to force the system to boot off of USB. Done that it successfully boots from USB. However when unplugging the USB-Drive the boot will fail due to extlinux.conf pointing to a missing boot drive.

In order to rescue the system you need to boot from USB... mount /dev/mmcblk0p1/ and edit extlinux.conf in the eMMC storage again so that rootfs points to the internal eMMC again. That's a bit of a pain.
It would be nice if one could specify a primary and a secondary boot device. Then one could specify USB as the primary and if that one isn't found the system could fallback to the secondary (in this case eMMC).

Is this possible?
A solution like that would be highly appreciated.

Thanks and keep up the excellent work and videos! I enjoy them much!

What version of L4T/JetPack
L4T/JetPack version: 4.6rev3

Which Jetson
Jetson: Jetson TX2 NX

[mohsinulbari]

Could you fix it somehow?

[HunterShinobiTitan]

I am using Jetson Nano Developer Kit. I solve it by just copying the extlinux.conf from the USB boot and paste it on the Emmc extlinux.conf. Make sure that you have the backup created on both storage.