Summary

Custom firmware image for the LS700 which can be booted into from a USB device using the serial console or flashed to the onboard eMMC.

Details

Installation Procedure

Boot from USB

Write the disk image to a USB device. In my testing only a few of my USB drives are actually recognized by the device and I haven't been able to determine a pattern. If one doesn't work it's worth trying again with a different one.

$ sudo dd if=output/images/disk.img of=/dev/sdx bs=4k
363520+0 records in
363520+0 records out
1488977920 bytes (1.5 GB, 1.4 GiB) copied, 0.428306 s, 3.5 GB/s

Insert the USB3 port and hold the "Function" button on the front when powering on the device to have the device attempt a USB recovery boot and boot the new image.

 * Starting /etc/init.d/S79r8152
 [ ok ]
 * Starting /etc/init.d/S79ubootenv
 [ ok ]
 * Starting /etc/init.d/S80dhcp-relay
 [ ok ]
 * Starting /etc/init.d/S80dhcp-server
 [ ok ]
 * Starting /etc/init.d/S91smb
 [ ok ]
 * Starting /etc/init.d/S99at
 [ ok ]

Welcome to Buildroot
buildroot login: 

Make persistent by writing to eMMC

NOTE: messing with the eMMC could probably brick your device. Typos or incomplete copy/paste of the commands below could have irreversible effects. Please be careful.

On my device the stock firmware was taking up about 1.5G of the 4GB onboard eMMC so it was pretty easy to partition some of the free space and write the new OS image to it.

I've created ls700_install.sh which automates the process of validating the relevant offsets/etc before adding a new partition and installing the buildroot rootfs to it.

# uname -a
Linux buildroot 4.9.119-buffalo-ls700 #2 SMP PREEMPT Sat Mar 22 22:08:55 CDT 2025 aarch64 GNU/Linux
# cd /boot
# ./ls700_install.sh 
1803+1 records in
1803+1 records out
7386156 bytes (7.4 MB, 7.0 MiB) copied, 0.28178 s, 26.2 MB/s
561+1 records in
561+1 records out
2297979 bytes (2.3 MB, 2.2 MiB) copied, 0.172587 s, 13.3 MB/s
14+1 records in
14+1 records out
61332 bytes (61 kB, 60 KiB) copied, 0.00399237 s, 15.4 MB/s
The operation has completed successfully.
The operation has completed successfully.
The operation has completed successfully.
mke2fs 1.47.2 (1-Jan-2025)
/dev/mmcblk0p6 contains a ext4 file system
        last mounted on / on Mon Mar 10 22:20:40 2025
Proceed anyway? (y,N) y
Discarding device blocks: done                            
Creating filesystem with 860155 4k blocks and 215136 inodes
Filesystem UUID: e4ffebe4-9fe8-4358-94af-25b6ffedc06c
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912, 819200

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (16384 blocks): done
Copying files into the device: done
Writing superblocks and filesystem accounting information: done

Reboot the device and it should now boot into the new environment.