equivalent copy-nand interface ideas for XO-1.5

[Daniel Drake]

On Sun, 2009-06-14 at 11:00 -0400, Paul Fox wrote:
> another possibility:  size the original fs image to the size of
> the data it will hold:  i.e., create a filesystem with no free
> space.  this will eliminate the sparseness issue when
> distributing.  use OFW to write this in a raw, filesystem-unaware
> manner.  mark the file system in such a way that the initrd will
> know (or perhaps it will simply guess, based on sizing) to resize
> the filesystem before mounting, in order that it fill the
> available space.  my impression is that the extN filesystems are
> fairly easy to grow in place?

Yes indeed.
Maybe a hybrid is called for.

We could produce the images at e.g. 3GB in size, to be sure that they'll
fit on any definition of "4GB flash storage".
We could distribute them in sparse tarballs as I described, and OFW
would parse that format and flash onto the target partition.
Then during first boot, the initramfs would grow the filesystem to fill
the 4GB.

I found out a bit more about tar's sparse format and I like the idea
more and more:
http://www.gnu.org/software/tar/manual/html_section/Sparse-Formats.html
http://www.gnu.org/software/tar/manual/html_section/Portability.html#SEC143
http://www.gnu.org/software/tar/utils/xsparse.html

Daniel