This is going to be for you to figure out:
So let’s look at the basic extlinux.conf file:
label Linux 5.4.58-armv7-lpae-x33
kernel /boot/vmlinuz-5.4.58-armv7-lpae-x33
append root=/dev/mmcblk2p1 ro rootfstype=ext4 rootwait quiet
fdtdir /boot/dtbs/5.4.58-armv7-lpae-x33/
First Line:
label Linux 5.4.58-armv7-lpae-x33
This is just a label and dumped on bootup, it’s value is not used for anything.
2nd line:
kernel /boot/vmlinuz-5.4.58-armv7-lpae-x33
This is kernel “boot file”, it’s a link to a raw file, access by u-boot:
debian@arm:~$ ls -la /boot/
total 10372
drwxr-xr-x 5 root root 4096 Aug 19 21:08 .
drwxr-xr-x 21 root root 4096 May 10 20:17 ..
-rw-r--r-- 1 root root 192123 Aug 19 21:08 config-5.4.58-armv7-lpae-x33
drwxr-xr-x 3 root root 4096 Aug 19 21:08 dtbs
drwxr-xr-x 2 root root 4096 Aug 19 21:08 extlinux
drwxr-xr-x 2 root root 4096 May 10 20:17 uboot
-rwxr-xr-x 1 root root 10404352 Aug 19 21:08 vmlinuz-5.4.58-armv7-lpae-x33 <- kernel file
3rd line:
append root=/dev/mmcblk2p1 ro rootfstype=ext4 rootwait quiet
This is our bootarg’s appended to the default cmdline:
debian@arm:~$ cat /proc/cmdline
root=/dev/mmcblk2p1 ro rootfstype=ext4 rootwait quiet
debian@arm:~$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
mmcblk2 179:0 0 3.6G 0 disk
└─mmcblk2p1 179:1 0 3.6G 0 part / <- Root Driver
mmcblk2boot0 179:256 0 2M 1 disk
mmcblk2boot1 179:512 0 2M 1 disk
4th line:
fdtdir /boot/dtbs/5.4.58-armv7-lpae-x33/
This is the directory containing all our device tree’s:
debian@arm:~$ ls -alh /boot/dtbs/5.4.58-armv7-lpae-x33/ | grep pico
-rw-r--r-- 1 debian debian 47K Aug 19 21:04 imx7d-pico-hobbit.dtb
-rw-r--r-- 1 debian debian 47K Aug 19 21:04 imx7d-pico-pi.dtb
So it’s going to be you to convert your Yocto sytem to use extlinux.conf for bootup.
But feel free to switch to Debian or Ubuntu at any time:
Regards,