Re: APEX and Debian
We also need to preserve the last block (128KiB), which holds the FIS directory, a 100+KiB unused area (we were considering using that to store the NPE microcode if we couldn't use the copy already in RedBoot, but we could also use that for the APEX configuration area if it is able to be in the middle of an erase block and preserve data before and after it) and the SerComm Trailer which must be in place for the SerComm upgrade tool and RedBoot first stage loader to work.
From: Marc Singer <email@example.com>
Date: Wednesday, Jul 19, 2006 11:46 am
Subject: Re: APEX and Debian
On Tue, Jul 18, 2006 at 03:20:15PM -0700, Marc Singer wrote:
Have I missed anything? Do we want to copy more than 2M of kernel?
We could copy 3.5MiB (4MiB - 256KiB - 128KiB - 128KiB) which is
everything except for Redboot, the sysconf block, and APEX.
I got this wrong. I mistakenly thought we only had 4MiB of flash, but we have 8MiB. So, it is reasonable to put two kernel images in flash such that one is a backup in the event that the main one fails.
Once we get the second stage working properly, I'll implement
something so that the user can switch to a backup image by holding the power button (or something like it) during startup. This means we'll have 7.5 MiB/2 for each kernel w/initramfs which I hope is enough.