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Failsafe mode
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== Failsafe mode

**Caveat:** This functionality only applies to SquashFS images, since they come 
with a read-only root partition. To verify whether your device uses SquashFS,
check for "SquashFS" either in the _LEDE_ image name or perform the following
check on your device:

 # grep squash /proc/mount

_LEDE_ allows you to boot into failsafe mode and override the configuration saved
on the JFFS2 overlay. It will revert to a few hard coded defaults stored in the 
SquashFS image. If your device becomes inaccessible, e.g. after a configuration 
error, then failsafe mode is there to help you out; it *cannot*, however, fix 
more deeply rooted problems like faulty hardware or a broken kernel. It is 
comparable to a reset, but not entirely the same - you will still be able to 
access your settings and restore them if desired, whereas a reset would just
wipe everything.

=== Entering failsafe mode

Make sure you use a wired connection, since the failsafe will disable your 
wireless connectivity.

To enter failsafe mode, follow one of the procedures listed below:

* Wait for a flashing LED and press a button;
* Wait (with a packet sniffer) for a special broadcast packet and press a button;
* Watch for a boot message (on the serial port) and press a key ("f") on the serial keyboard.

Usually, the first procedure is the easiest one. However, do consult the available
documentation for your device, as there is no default button assigned as a reset 
button and not all procedures work on every device. Whichever trigger you use, 
the device will enter failsafe mode and you can access the command line with SSH 
(always possible) or a serial keyboard. OpenWrt releases (15.05 and before) offer 
a telnet connection in this state but no SSH.

=== Fixing or wiping your settings

Once failsafe mode is triggered, the router will boot with a network address 
of 192.168.1.1/24, usually on the 'eth0' network interface, with only essential 
services running. Using SSH or a serial connection, you can then mount the 
JFFS2 partition with the following command:

 # mount_root

After that, you can start looking around and fix what's broken. The JFFS2 
partition will be mounted to '/overlay', as under normal operation.

If you want a clean slate, there's no need to flash again; just enter the 
following command and your device will be reset.

 # firstboot

=== Settings not being saved

When your device seems to save settings but loses them upon every reboot,
this could mean that overlayfs is corrupted. You can fix this by SSH-ing into the
device and issuing the following command to reset your JFSS2 partition:

 # jffs2reset

While essentially doing the same thing as 'firstboot', this rewrites the flash 
area of the JFFS2 file system instead of formatting it.

More specific instructions will be provided in the wiki.

**WIP**