EM Mode

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EM Mode

EM Mode officially means Engineering Mode, but we also call it Emergency Mode. If the LinkStation encounters a serious error with the hard drive or file system it will enter EM Mode. When in EM mode the LinkStation loads its file system from the flash instead of the hard drive. The LinkStation can be seen on the network with the IP address but can only be reached via ping or the LinkStation firmware flasher. The firmware updater is able to find the Linkstation, only if UDP-Port 22936 is open. This is always true in EM Mode. An FTP server appears to be running but we currently don’t know the username/password and what can be done via FTP.
You will need to correct the hard drive error and re-flash the firmware to get the LinkStation out of EM mode. Some users have reported success with installing a blank hard drive (in ext3 format) and flashing the firmware.

LED Analysis

Take a look at the LED analysis for your LinkStation:

Frequently asked questions about EM Mode

From the following forum thread: The Linkstation Community Forum / Everything else / Clarifications regarding big drives and EM Mode - FAQ Entries
EM Mode really is a mystery, there are some misunderstandings here:

1) I read several times that some others wrote that pressing the reset button while powering the linkstation gets the LS into EM Mode.

Thats simply not true. If you start your LS that way you will get into something lets call "Christmas Tree Mode"...all leds of the LS are blinking together. This mode in reallity just bypasses the watchdog. If ppc_uartd or avr_evtd are missing the boxes stop working after 5 minutes. In christmas tree mode these processes are not needed. One supposes this was a way to deal with the diskchecks that take place from time to time and which are time consuming (they need more than 5 minutes). Mindbender changed openlink 0.73b so that ppc_uartd (which is currently used...but will be replaced soon with avr_evtd) starts earlier. So this problem should not happen anymore in OpenLink.

2) How do we get into EM Mode? how do we get out of it again? whats the status?

This is where everything is prepared to change. Lets start with the current status and then comment what is planned:

General Info

There is always a partition in flash that holds an endless OKOKOK... sequence inside. Just look at the content of the devices by cating the content of the flash-partitions:

For example for a LS1:

cat /dev/fl3 >/fl3_dump

For the HG use this instead:

cat /dev/mtd2 >/mtd2_dump

In the boot process after the kernel is loaded, the kernel checks if OKOK.. is inside this partition or not. If yes, then the Operating System from the HDD is booted. If no, then EM Mode is loaded from the Ramdisk which is also stored in flash inside firmimg.bin

Current Status

How to get into EM Mode:

It depends if you risk to open the LS or not. modifying the content of the correct flash partition and therefore triggering EM Mode:

1. Hard Drive Error
  • If you open the LS and remove the hard drive; powering the LS without having the Hard Drive attached.
  • If you delete or corrupt the contents of /hda1 somehow, your LS may enter EM Mode on reboot
  • If you install a unpartitioned/blank hard drive, your LS may enter EM Mode when turned on.
2. Via commandline while stock kernel

(can be dangerous if wrong device is echoed to)

  • LS1: - 2.4.17
echo "NGNGNG" > /dev/fl3 
  • HG: - 2.4.20
echo "NGNGNG" > /dev/mtdblock2 
  • HS: - 2.4.20
echo 'NGNGNG' > /dev/mtdblock2

after reboot the LS should boot from Flash instead of from the HDD...

3. Starting the flashing process via the firmware updater and then just cut the network connection

Mindbender has gotten his LS1 several times into EM Mode by starting the flashing process via the firmware updater and then just cutting the network connection

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It is strongly recommended NOT to do it this way. It did not work everytime but if it did not work it also did no harm.

How to get out of EM Mode:

1. Reflashing via the firmware updater

Reflashing via the LinkStation firmware flasher is the only possibility currently for the normal user.


Screenshot of Planned EM Mode

How to get into EM Mode:

1. Pressing the reset button longer than 20 seconds

After avr_evtd is built-in into OpenLink & FreeLink you will be able to get your LS into EM Mode simply by pressing the reset button longer than 20 seconds. This is already working really well, it just has to be integrated.

How to get out of EM Mode:

1. Reflashing via the firmware updater

Reflashing via the LinkStation firmware flasher of course will get you out of EM mode.

2. Telnet access

In EM Mode you will have telnet access in the future. Mindbender has already created Telnet and FTP enabled ramdisks inside new firmimg.bins which you can use to partition the hdd to your needs while in EM Mode. Executing "write_ok" gets you out again.

The stock firmimg.bin does NOT have telnet + ftp enabled. These firmimg.bin here are enhanced versions which have telnet + ftp enabled.
This makes it possible to fix various problems that normaly would lock you out of the box
and that would demand a complete reflash via the firmware updater.

the firmimg.bins from here can be used: