FreshTomato Wiki

If yout want to use the crashlog feature you have to use the AIO files/images.
VPN files/images do not include crashlog. (You can also create a custom image with CRASH_LOG=y)
Note: only available for ARM router!

1. Check partitions for your router

Example:

root@RT-AC56U:/tmp/home/root# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00080000 00020000 "boot"
mtd1: 00180000 00020000 "nvram"
mtd2: 01e00000 00020000 "linux"
mtd3: 01c52be0 00020000 "rootfs"
mtd4: 06000000 00020000 "brcmnand"
mtd5: 03fe0000 00020000 "jffs2"
mtd6: 00020000 00020000 "crash"
root@RT-AC56U:/tmp/home/root#

⇒ mtd6 (“crash”) is what we need for RT-AC56U (in this case)

2. prepare crashlog (needs to be done each time for the next/new crashlog file)

Example:

root@RT-AC56U:/tmp/home/root# mtd-erase2 crash
Erase MTD crash
Erase MTD crash OK!
root@RT-AC56U:/tmp/home/root#

3. let the router crash! :)

4. Get/save the crashlog file

Example:

root@RT-AC56U:/tmp/home/root# cat /dev/mtd6 > /tmp/crashlog.bin

Get the crashlog.bin file from the /tmp directory with FTP, SFTP or SCP (using for example, WinSCP)

Example for saving to USB:

root@RT-AC56U:/tmp/home/root# cat /dev/mtd6 > /tmp/mnt/ROUTER_USB_NAME/crashlog.bin