Soekris BIOS upgrade using cu(1) and lsx(1)

Here’s a quick HOWTO for updating a Soekris net4801 BIOS using cu(1) and lsx(1) from comms/lrzsz under FreeBSD.

First, establish contact to the BIOS using something like ‘cu -l /dev/ttyU0 -s 19200’ adjusted to fit the device node and speed used in your setup. Then follow these steps:

  1. Press Ctrl+P to enter the Soekris BIOS monitor
  2. Type download -
  3. Press ~C
  4. Type lsx /path/to/b4801_131.bin

If the XMODEM transfer was successful, continue with the following steps:

  1. Type flashupdate
  2. Type reboot
  3. Press ~. to exit cu(1)

That’s it! The BIOS should now be updated :)

One thought on “Soekris BIOS upgrade using cu(1) and lsx(1)”

  1. On Linux, I had to use “~+” instead of “~C”, with the binary in my home directory. Also, the command for the 1.33 flash is “sx -X b4501_133.bin”. Good luck!

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