[Server-devel] Root fs on XO1

[George Hunt]

Hi Jerry, et al,

The motherboard flash on an XO1 is 1GB. The kernel, rootfs, provided by
OLPC Boston for the XO1 occupies 745MB. The server software (XSCE) we have
been adding on top of the OS occupies about 1.3GB.  So obviously an
additional SD card is required.

My first approach has been to start with a vfat formatted SD card, change
its format to ext4, without changing its partition layout (I think this
avoids creating erase block/OS write mismatch, which slows and wears SD
cards prematurely). Then I have been copying large chunks from the JFFS to
the SD card, and sym-linking to it, so that additional yum install
operations are diverted to the SD card.

Recently, Jerry has suggested that I just ignore the motherboard jffs
flash, and run entirely off the SD card.  I've been studying how to
accomplish this.  It looks to me like the <OS>.img file available for the
XO1 is in jffs2/mtd format which would be appropriate for "dd"ing directly
to the motherboard flash, but probably not correct for "dd"ing to an SD
card.

So here is my question: Does it make sense to let the openfirmware bios
write the OS image to the jffs on the motherboard, and then for me to rsync
that OS, as data,  to an ext4 formatted (not repartitioned) SD card? If I
do this will the presence of a signed kernel on the SD card cause the boot
loader to choose the SD card, ignore JFFS, even if the XO is still secured?

George
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