> On 12. apr 2017, at 9:04, Julian Elischer <jul...@freebsd.org> wrote: > > On 12/4/17 12:34 pm, Colin Percival wrote: >> [CCing freebsd-cloud, which is the right place for discussions of >> FreeBSD/EC2] >> >> On 04/11/17 21:03, Julian Elischer wrote: >>> In Amazon ec2 they have no console access (though I heard rumors that it was >>> available I have not seen any sign of it) so I'd like to put a "recovery >>> partition" into an AMI. >>> The trick is how to convince it to boot to that instead of the regular >>> action. >> Can you get what you want via gptboot's support for selecting the partition >> to boot via "bootonce" and "bootme" flags? > not if you can't get onto to the machine. > When I talk about a recovery partition I mean it in the same way that apple > means it.. > "system won't boot? press the power button and hold down the 'option' key. > it will give you the option to boot to a recovery mode" > (* actually I can't remember the keys but you get the idea..) > > in our case we would like to be able to recover a customer's AMI by giving a > simple set of instructions over the phone. > We can assume they know how to get into the amazon menus, but we would like > to not have to assume much more. > >> >>> The ideal thing would be if there was way to 'influence' one of the smbios >>> values in some way, and have the boot code see it, but I'm open to any >>> suggestions. >>> I really need only 1 bit of information to get through. >>> >>> Possibilties include "changing the VM to have only 2G of ram" (we'd never do >>> that in a real machine). >>> or maybe temporarily removing all the disks other than the root drive? >>> Almost >>> anything I could do to signal the boot code to behave differently. >> I don't think adding/removing disks will be useful, since the extra disks >> will >> be Xen blkfront devices; AFAIK the boot loader doesn't know anything about >> these. (The boot device is also a blkfront device but gets ATA emulation for >> the benefit of boot loaders.) >> >> Maybe you can repurpose some of the logic used for booting over NFS? I've >> never heard of people booting over NFS when the initial bootstrap comes from >> disk rather than PXE, but I assume it's possible...? > > Oh I've done it, in the past but you still have the same issue.. > how do you signal the boot code to do this? > > (does an AMI have a bios capable of doing network operations?) I was thinking > about whether we could add a really simple xn driver into the bootcode to > allow > us to have an console of sorts (accessible from an adjacent machine only??) > > >
basically you want what zfsbootcfg does but in reverse — with fallback to recovery… rgds, toomas _______________________________________________ freebsd-xen@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-xen To unsubscribe, send any mail to "freebsd-xen-unsubscr...@freebsd.org"
