[OLPC-devel] just verified: 2306 + olpc + linux kernel works.

[Jim Gettys]

On Sat, 2006-05-27 at 13:45 +0100, David Woodhouse wrote:
> On Fri, 2006-05-26 at 21:06 -0400, Jim Gettys wrote:
> > The flash on the iPAQ had bits you could set that would write protect
> > sectors of the flash (does the NAND flash we have have similar
> > capabilities?  I dunno). That meant you couldn't write from Linux
> > without first unprotecting those sectors 
> 
> We don't have that facility.

Too bad....

> 
> An option which others have taken is to put two copies of the bootstrap
> code into partitions in the flash, and have a failover mechanism so that
> one can be updated while leaving the other intact. Even if we don't want
> to update a live system, that fallback mechanism can perhaps be a useful
> safety net for us.
> 

Yes, my new motherboard in my server has exactly this facility.  I saw
this as a major feature when I was last in the motherboard market, as
I'd bricked my previous mother board trying to upgrade it, and was
frustrated.

In fact, we can do this strategy for the main bootloader itself if we
like; have it checksum another kernel and load it, which loads then real
kernel.  In that sequence (if it doesn't take too long), we would
seldom/never need to update the primary bootloader Linux in the serial
flash.  The one we'd update normally would be in NAND, and we'd leave
the primary boot loader kernel with the "restore in extremis" alone
under almost all circumstances.

How long does it take to get a kernel running?
                                             Regards,
                                               - Jim

-- 
Jim Gettys
One Laptop Per Child