Date: Wed, 12 Apr 2017 14:34:24 +0800 From: Julian Elischer <julian@freebsd.org> To: Toomas Soome <tsoome@me.com> Cc: freebsd-cloud@freebsd.org, FreeBSD Lists <freebsd-xen@freebsd.org> Subject: Re: amazon/xen... any way at all to pass a message/signal/semaphoere/morse-code to the boot loader? Message-ID: <66834e02-3746-1424-6388-1730d06a1b26@freebsd.org> In-Reply-To: <3A0FDF0B-B3CC-4CB7-AF9F-DC7CB60A6B5A@me.com> References: <bf761b5c-63ad-bb14-4a9b-4e1fedced5bd@freebsd.org> <0100015b6070d24d-a23d7d90-11c0-4065-9bd0-0fc71b5874d6-000000@email.amazonses.com> <6f1c694d-1bb7-cdcc-daed-fd2e25dc2a28@freebsd.org> <3A0FDF0B-B3CC-4CB7-AF9F-DC7CB60A6B5A@me.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 12/4/17 2:09 pm, Toomas Soome wrote: >> On 12. apr 2017, at 9:04, Julian Elischer <julian@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… yes, that is also a possibility N failed boots in a row.. > > rgds, > toomas > > >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?66834e02-3746-1424-6388-1730d06a1b26>