EM Mode

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From the following forum thread: The Linkstation Community Forum / Everything else / Clarifications regarding big drives and EM Mode - FAQ Entries

Contents

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 192.168.11.150 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.

Take a look at the LED analysis for your LinkStation: LS1, LS2, HG

Frequently asked questions about EM Mode

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 i 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 this processes are not needed. i suppose 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...i changed it in openlink 0.73b that ppc_uartd (which is currently used...but will be replaced soon with avr_evtd) starts earlier....so this problem should not happen anymore.

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 for a 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...like "cat /dev/fl3 >/fl3_dump" for example for a LS1...use /dev/mtd2 for the HG instead. in the boot process after the kernel is loaded it is checked by the kernel if "OKOK.." is inside this partitions or not. if yes then the Operating System from the HDD is booted. if no, then EM Mode is loaded....in fact the Ramdisk which is also stored in flash inside the firmimg.bin. EM officialy means "Engineering Mode", but we also call it "Emergency Mode".

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. If you open the LS: powering the LS without having the HDD attached
2. Via commandline while stock kernel

(can be dangerous if wrong device is echoed to)

  • LS1:
echo "NGNGNG" > /dev/fl3 - 2.4.17
  • HG:
echo "NGNGNG" > /dev/mtd2 - 2.4.20
  • HS: there is no proof...but it suppose it is the same as for the HG.
  • LS2: the info from: Information/MIPSelFlashROM is quite incomplete...i am simply not sure. i would need one for testing.

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

I got my LS1 several times into EM Mode by starting the flashing process via the firmware updater and then just cut the network connection

Nuvola apps important.png 
WARNING!

Strongly recommend NOT to do it this way it did not work everytime


But if it did not work it also did not do any harm, I never had big problems with that.

How to get out of EM Mode:

1. Reflashing via the firmware updater

Thats the only possibility currently for the normal user.

Planned

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. i just have to integrate it.

How to get out of EM Mode:

1. Flashing

Flashing of course also will get you out of EM Mode

2. Telnet access

In EM Mode you will have telnet access in the future...i already created telnet + 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.

Everything else just needs some work to integrate. but there is a high ambitious goal I set for myself. I want to totally rebuild the Ramdisk of EM Mode myself and enhance it with much new functionallity (support for XFS) to make it a good preparation and rescue system.