Alternate distros from SD

[Jim Gettys]

Cool.

On Thu, 2008-08-14 at 11:06 -0400, Daniel Drake wrote:
> Hi,
> 
> As mentioned yesterday, me and Bobby spent a few hours working towards
> scripting the process of fixing up a SD-based regular distribution
> install to work on XOs...
> 
> We started with Fedora 9 and had to make the following changes:
>  - OLPC kernel (testing branch) and modules with a slightly modified
>    config (building stuff into the image to avoid needing an initramfs)
>  - /dev/console needs to be added to Fedora install when you aren't 
>    booting with an initramfs
>  - /boot/olpc.fth boot script needed
>  - Display settings from XO's xorg.conf required to avoid things 
>    looking really funky
> 
> Things work quite well from that point. Wireless works, suspend too,
> mouse/keyboard just fine, ...
> 
> More on the initramfs thing:
> Fedora doesn't like being booted direct from disk when the disk is
> mounted read-only (it tries to write to various files). So we had to
> drop the 'ro' boot parameter. That makes Fedora attempt to e2fsck the
> root partition when it is mounted read-write, so you get something like
> the following prompt on each boot:
>  running e2fsck on a mounted partition is really dangerous, continue? 
>  (y/n)
> 
> We then used the F9 initramfs, which worked (despite about 20 errors
> that it couldn't find modules or modules.dep, as you might expect). The
> best solution may be rolling a minimal initramfs for our case.
> 
> After figuring out the above, I wrote scripts that will take a SD card
> where F9 has been vanilla-installed, and it will make the above changes.
> TOTALLY UNTESTED but if you want to look, its at
> git://dev.laptop.org/~dsd/XO-alt-distro
> 
> Will probably spend a few more hours on this on Friday or Monday
> evening. We also want to look at the latest alphas for F10 and Ubuntu
> intrepid.
> 
> I also looked at the USB key that Jim gave me, with his custom minimal
> fedora spin. I added my OLPC kernel from above and booted manually using
> openfirmware. The initramfs is absolutely needed here because there is
> no root fs on the card - the initramfs presumably mounts the squashfs
> image and then pivots into that. I reused the existing initramfs
> unmodified.
> That initramfs tried to load various modules and failed as expected, but
> it has logic to abort when such failures are detected. Didn't get any
> further than that. It'll certainly require modifying or re-rolling the
> initramfs to get this booting on XO.

Yes, it probably loads some modules from the image, and loses; we need
to respin the image so the modules and the booted kernel matches, I
suspect.

If the live CD image then boots, install to disk would be one way to get
it onto the SD card.

> 
> Another funky bug: sometimes sdhci fails to initialize during boot,
> giving an odd error message which we didn't write down (some kind of
> command timeout). This is odd given that we're using an OLPC kernel and
> I don't think we've seen this on the XO?
> 

Interesting. Deepak, any clue?
                               - Jim

-- 
Jim Gettys <jg at laptop.org>
One Laptop Per Child