Snozberry

So, I've figured out how I'm going to do it. Rather than have one large internal flash disk with the whole system on it, I'm going to use two flash disks. This way, I can keep the the system's root filesystem on my PC and won't have to disassemble the whole unit every time I want to update the system software.

I could perform updates from the device itself, but that wouldn't allow me to manually strip things down before sticking them on the flash. Also, it would require more writes to the flash than just periodically updating everything at once. As if those weren't enough reasons, in the event of any failure on the handheld I probably wouldn't have a well-maintained, accurate backup tree on my PC.

This approach does mandate that I either disassemble the unit to upgrade the kernel, or update said kernel from the device itself, but I'm not particularly bothered by this. First off, updating the kernel is actually quite simple - basically involving nothing more than using lilo to write the MBR with a couple of new files. And since it's much easier for me to create those files on my PC, I will always have them there in case something goes wrong on the handheld. Keeping four files in sync across the two devices is much easier than a whole filesystem full of files.

The setup will look like this:

• Use a small (cheap) 8MB compact flash disk inside, on the IDE bus to boot the device. This card will have nothing but a kernel and an initrd image on it.
• When the device boots, the kernel will be loaded, it will mount the initrd image in RAM and load up some key drivers - namely the PCMCIA drivers.
• Once PCMCIA is up, I'll have access to the full size compact flash card in a PCMCIA adapter (only $9!). This card will then be mouted as the root filesystem. As I said before, the benefit of of this is that I will be able to easily remove the root card and update it with new software from my PC.

Tonight I'll stop by CompUSA and buy a PCMCIA comact flash adapter. I can't seem to find the little 8MB card that came with Jenny's digital camera, so I'll probably buy one of those, too. Then, my goal for tonight is to build a functioning initrd image to mount ("pivot") the root partition to the PCMCIA adapter compact flash card. I'm hoping this will go quickly and I'll have time to start building my root filesystem. At the very least, I'd like to have a shell up and running on the LT by bedtime (which is early tonight).

Posted by reds at December 9, 2003 02:40 PM