NAND Full Requirement
erik at laptop.org
Tue Jul 22 16:16:58 EDT 2008
On Tue, Jul 22, 2008 at 04:01:35PM -0400, Greg Smith wrote:
> Hi All,
> Here's the requirement for Uruguay NAND full situation.
> I need this fixed ASAP.
> - The XO must always boot up to sugar including allowing access to the
> journal. That is no matter the fullness of the NAND
> - If the NAND has less than nnMB (50?) free, warn the user that they are
> low on space.
> - Must be installable on 656 in the Uruguay configuration
> - Must not delete any user created files
> - Must not disable any activities or other functionality
> So far they have:
> - a dialog box which warns when you get low on space
> - Chris's script which allows deleting stuff automaticaly but probably
> user stuff
> What else they want, not sure... I will talk to Emliano ASAP and let you
> Erik will propose one solution (related to RamFS I believe).
On boot, check NAND discomfort level. If high, use unionfs(4) to mount
a read/write tmpfs over top of a read-only jffs2 rootfs. Set unionfs
flags to enable file deletion from the 'ro' root partition (or if this
is impossible, mount the fs in another location to allow deletions).
Set a flag to tell olpc-session or Sugar to enter into a deletion
This solution theoretically allows all software to run an a NAND-full
machine. Thus students who arrive at school with a NAND-full machine
could still work with their XO through lessons and manage flash cleanup
as time is available. Requires minimal code-level changes to enable.
Working on this solution may distract from efforts to get our system to
boot cleanly on top of a read-only root fs. C. Scott and others have
suggested that we ultimately want to do this.
Currently unionfs is untested on the XO. I am waiting for a
unionfs-enabled kernel (currently building). Theoretically it will
work, as per every Linux livecd under the sun.
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