Archive for the ‘Cobalt Raq3’ Category

Kernel Update Kills Raq

April 25th, 2009 No comments

A week or so ago, I started playing about with the Raq in the hopes of being able to quickly get it doing something (and preferably hidden in a cupboard and not on the desk next to the bed).

I quickly got ahead of myself, and in the process of trying to update it managed to completely screw it to the point where all it would do is display Kernel Panic on the LCD Screen. Turns out that by updating the kernel on the eeprom, it can no longer boot its OS.

If I understand correctly, then the boot sequence for the Raq3 goes like this (when booting from the hard disk).

  1. Decompress + Load Stage 1 kernel from the eeprom.
  2. Initialise the LCD Screen and buttons.
  3. Allow the HDD to spin up and stabilise.
  4. <Boot Menu (if triggered)>
  5. Decompress + Load Stage 2 kernel (from specified boot partition)
  6. Continue standard bootup…

There are some interesting things to note about this. For a start there is no bootloader (eg lilo or grub) as you would need on most hardware as it is built into the eeprom. The eeprom on a Raq3 is limited to 1024k making it quite hard to fit a modern kernel on it, which leads to some interesting issues.

The Raq3’s built in OS uses a customised version of RedHat and boots a linux-2.2 (iirc) kernel which is completely obsolete and has been for quite some time (we are currently at 2.6.29-r1, see this for some idea of context), which then passes off to a linux-2.2 stage 2 kernel on the hard drive.

The latest possible kernel for the eeprom is a linux-2.4.24 kernel, which is still obsolete in terms of current features, but has the power to let us do something clever. There is a sourceforge project you can get this latest cobalt-rom (2.10.3) release (containing the afformentioned 2.4 kernel) but bear in mind the project was last touched in 2003.

When I updated the eeprom to the 2.4 kernel, its quite obvious that it would freak out when trying to load the 2.2 kernel (stage 2). -Or is it the 2.2 freaking out at being loaded by a 2.4?

It was at this point it got shelved for a couple of weeks whilst I flailed about the great intertubes trying to find a fix.

One thing became clear; The only way out is up!

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