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Debian/NSLU2 FAQ

This is a page of frequently asked questions for NSLU2. Please see the Troubleshooting page for troubleshooting tips. A few of the items that previously existed on this page have been moved to the Troubleshooting page.

If you are using Debian on you NSLU2, you should probaly use the Debian lists. For details see: 

    http://lists.debian.org/

Warning: the Debian lists are not spam-protected like the Yahoo-hosted NSLU2 lists. You might want to use some sort of "throw away" email address to post to them from.

What do the LED colours and activity mean with Debian/NSLU2 ?

The meaning of the colours and activity are documented in /usr/share/doc/nslu2-utils/README.Debian on a Debian/NSLU2 system.

How do I get a copy of my currently flashed image ?

$ cat /dev/mtdblock* > image

How can I reduce the memory footprint of my Debian install ?

Debian-Etch comes with two Network sharing protocol's enabled by default and if you then add SAMBA thats a total of three
  1. Netatalk
  2. NFS
If you are not planning on communicating with Apple shares/printers consider removing the netatalk package. You will free 4 Mb of RAM. Likewise if you are not planning on sharing out files via NFS, this service should be disabled. You can follow the procedure below, or use rcconf (apt-get install rcconf). 
mv /etc/rc2.d/S20nfs-kernel-server  /etc/rc2.d/K20nfs-kernel-server
mv /etc/rc2.d/S21nfs-common  /etc/rc2.d/K21nfs-common
Also the default Debian install has a message transfer agent enabled by default (exim4). If this is not needed consider removing it to free up 8Mbytes of RAM.
Switching the default shell from *bash* to *dash* saves another chunk of memory
See also http://www.cyrius.com/debian/nslu2/reducing-memory.html

How do I change the function of the power button on the NSLU2 to shut the system down as opposed to rebooting it?

Replace the line the /etc/inittab
ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now
with
ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -h now
remember to run
telinit q
to reload the file

How do I know why my NSLU2 failed to boot when I have no console?

Attach the USB stick/drive to another computer and check the logs in <path-to-USB-drive>/var/log. You can also edit the configuration files to implement a fix.

Why isn't my real time clock keeping time?

The NSLU2 will not keep time with the Debian 2.6.17 kernel. The problem has been fixed in 2.6.18, which is the Linux kernel that is shipped with Debian GNU/Linux 4.0 (etch). If for some reason you can't upgrade your kernel, you can temporarily fix the problem without by using tickadj to set the kernel ticks to 10101. You need to do this every time the NSLU2 is turned on.
Note by titioft: I have the latest RC2 Debian kernel "2.6.18-5-ixp4xx #1 Sun Dec 23 05:17:39 UTC 2007 armv5tel GNU/Linux" the problem is not fixd. Adding tickadj parameter did not change the problem; I am gaining 10 minutes every 1 1/2 day. My NSLU is runnign realtime monitoring of my utility meter and manage my X10 Home automation system. Time is a critical feature in such an environment (like starting your coffee machine at 7am etc....). I have my ntp dameon running all the time. But it does not sync time that often.... When I shutdown restart the ntp dameon it syncs and put time back on. Any idea where i can find progress on this? -- Please use the mailing list to report problems and ask for help.

Why is apt-get returning a segmentation fault?

If apt-get quits with a 'Segmentation Fault', remove the APT cache files in /var/cache/apt.
rm -rf /var/cache/apt/*.bin
Then rerun apt-get again. This problem was caused by a bug in the Debian kernel and has been fixed in the kernel source version 2.6.18.dfsg.1-9. See Debian bug #401980 for more information.

How can I avoid swapping / beating up my flashdrive?

The default debian install doesn't know that you only have 32 MB of RAM, so to save memory, you can tweak what you're running by default. One place to do this is in inittab - comment out the getty running on the serial port, and comment out the virtual terminal gettys. Also, if you chose Fileserver as an install option, be aware that you're automatically running NFS, Samba AND Appletalk - surely you can disable some or all of them. I did this, and was able to run my Slug w/no swap enabled. Make sure you disable ipv6 if you don't need it, and check `lsmod` output to see if there's crud in there that you don't need.
If you install to flash, you'll want to spare it as many writes as you can, so mount it with the 'noatime' parameter. Set the syslog defaults in /etc/default to "-m 0" to disable periodic MARK entries to the file. Specifically, add "SYSLOGD="-m 0" to /etc/default/syslogd.

How do I get X applications to correctly forward over SSH to my X server with Debian/NSLU2 ?

To make X forwarding work, you need:
  1. An X server on your local machine
  2. Access to the X server from your ssh client (running it in an xterm works)
  3. You need to connect to the NSLU2 with ssh -X
    (you must specify -X or it won't work; you may be able to get around this by changing one of ssh's configuration files)
  4. You need xauth installed on the NSLU2 (it's in xbase-clients Debian package so do apt-get install xbase-clients as root)
Now, just ssh -X user@NSLU2_IP_ADDRESS should allow you to re-display Xwindows applications to your X server.
Thanks to David Given for these instructions.

How can I install / compile additional programs / drivers?

How can I recover from a bad FLASH?

  1. Use upslug2 or the Linksys utility to write the latest Debian installer on the NSLU2
  2. Connect to device and proceed through the menu system until you have retrieved the pieces needed to access your USB driver. Do not re-partition it!
  3. Exit into a shell
  4. Mount the drive under /target
  5. If you have any swap partition, activate it with swapon
  6. Finally execute: 
mount -o bind /dev/ /target/dev
mount -t proc none /target/proc
chroot /target
flash-kernel
exit
umount /target/dev
umount /target/proc
umount /target
reboot

External resources

http://www.cyrius.com/debian/nslu2/reducing-memory.html Reducing memory usage http://www.cyrius.com/debian/nslu2/linux-on-flash.html Reducing wear and tear on flash drives