Re: amazon/xen... any way at all to pass a message/signal/semaphoere/morse-code to the boot loader?
I keep an extra EBS volume handy that has a simple recovery image. If I get stuck into a trouble, I change the normal boot disk to sdb, and attach my recovery volume as sda1. Essentially, the extra volume is my "recovery partition". To make it cheaper, keep only a snapshot of it. Same idea on Google Compute Engine. On Apr 11, 2017 11:34 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? > > > 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...? > > -- > Colin Percival > Security Officer Emeritus, FreeBSD | The power to serve > Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid > ___ > freebsd-cl...@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-cloud > To unsubscribe, send any mail to "freebsd-cloud-unsubscr...@freebsd.org" > ___ 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"
Re: amazon/xen... any way at all to pass a message/signal/semaphoere/morse-code to the boot loader?
[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? > 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...? -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid ___ 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"
amazon/xen... any way at all to pass a message/signal/semaphoere/morse-code to the boot loader?
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. 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. ___ 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"