Locating config files on SD card

Installing and Using OpenWrt
1

hi

I have a squashfs based install on a SD card for a APU4 system, and I messed up the configuration...
I cannot reach the console using SSH.

I have misplaced my null-modem cable :frowning:

I can take the SD card out, but I do not know where the config files are located...
I see the /dev/sda1 is the boot partition,
/dev/sda2 is the rootfs in a ro-squashfs...

Where is the overlay partition located?
Is it possible to mount the overlayfs with the squash-fs on another x86-64 system like a rpi4, over a SD card reader ?

G

2

hi

I hate why they have to have a hidden f2fs !!!!
I was able to address this...

I flashed another SD card...
then in that bootup I see

root@OpenWrt:~# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/root                 3072      3072         0 100% /rom
tmpfs                  2005676       904   2004772   0% /tmp
/dev/loop0              257152     45636    139836  25% /overlay
overlayfs:/overlay      257152     45636    139836  25% /
/dev/sda1                16112      3876     11912  25% /boot
/dev/sda1                16112      3876     11912  25% /boot
tmpfs                      512         0       512   0% /dev

Next I check the loop config

root@OpenWrt:~# losetup -alv
NAME       SIZELIMIT  OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC
/dev/loop0         0 3014656         0  0 /sda2       0     512

So basically they have a "hidden partition", which starts at an offset of 3014656 from the start of sda2 !!!!

Next I load up my original card on my RPI4 running buster (can be any linux system) and attach the SD card on a USB reader.. it shows up all the partitions...

$> apt-get install f2fs-tools
$> losetup -fP -o 3014656 /dev/sda2 
$> losetup -alv
NAME       SIZELIMIT  OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC
/dev/loop0         0 3014656         0  0 /dev/sda2   0     512

Creates a loop device for the hidden partition !!!

next

$> mount /dev/loop0 /mnt/
$> find /mnt/ | grep config.network
$> vi /mnt/upper/etc/config/network
# FIX/REVERSE my changes
$> sync
$> umount /mnt/
$> losetup -d /dev/loop0
$> sync
# Remove SD card from linux system..

Now I think I am back in business....

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