Date: Wed, 12 Apr 2017 07:13:07 +0000 From: Colin Percival <cperciva@tarsnap.com> To: Julian Elischer <julian@freebsd.org>, freebsd-cloud@freebsd.org Subject: Re: amazon/xen... any way at all to pass a message/signal/semaphoere/morse-code to the boot loader? Message-ID: <0100015b61023a42-c292f9c6-c73d-4901-85ac-90bcdaaa9ada-000000@email.amazonses.com> In-Reply-To: <6f1c694d-1bb7-cdcc-daed-fd2e25dc2a28@freebsd.org> 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>
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On 04/11/17 23:04, Julian Elischer 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. Well, I meant that you'd set this up in advance, so that if it can't boot the normal partition it would automatically fall back to the recovery partition. >> 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??) Oh, good point. No, the boot loader doesn't know anything about PV drivers, and there's no emulation, so you can't do anything networky from the boot loader. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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