On Thu, 31 Jan 2013, Wolfgang Denk wrote: > Dear Robert, > > In message <alpine.DEB.2.02.1301310731270.7034@oneiric> you wrote: > > > > that is, a single u-boot and config in flash, followed by a pair of > > kernel/rootfs partitions, that is remotely upgradeable by, from > > userspace, determining the "older" (backup) of the pairs, overwriting > > that pair with a new pair, then flipping the switch in the u-boot > > configuration to always boot the newer kernel and rootfs (with an > > emergency revert to the backup pair under circumstances i haven't > > imagined yet). > > The emergency revert usually relies on two things: > > - Watchdog support that will reset (reboot) the system reliably in > case the Linux kernel does not boot or does not manage to start the > user space control application that will trigger the watchdog. > > - The "boot counter" feature that will allow to run an alternativce > boot command (i. e. booting from the backup) in case the number of > boot attempts exceeds the set limit. > > > it *looks* fairly straightforward, but while that's a nice write-up, > > it does warn right up front that it hasn't been implemented so if > > anyone has done something like this they care to share, that would be > > delightful. > > Things like that have been done a number of times before; the fact > that such features as watchdog support and boot counter were added to > U-Boot are an indication for this. However, in the cases known to me, > the actual implementation was done as shell scripts (i. e. environment > settings) which were not published.
ok, i'm going to clear my schedule for the day and just read the u-boot manual cover to cover finally -- it will probably resolve a lot of my questions. if it's all right, i might update some of the manual wiki pages, like this one that corresponds to the patch i just submitted: http://www.denx.de/wiki/view/DULG/HowCanIAccessUBootEnvironmentVariablesInLinux where that comment should read: # Configuration file for fw_(printenv/setenv) utility. if it's anything more than just a trivial fix, i'll ask first. rday p.s. just edited that page, hope i did it correctly. onward ... -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ======================================================================== _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
