VM on bhyve not booting
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Last night I installed updates on my FreeNAS box and rebooted it. As expected my network died, but then it never came back, which I hadn’t expected.
My FreeNAS box provides backup storage space, a local Debian mirror and a mirror of talks from recent conferences. It also runs a couple of virtual machines and one of these provides my local DNS resolver.
I hooked up the VNC console to the virtual machine and the problem looked to be that it was booting from the Debian installer CD. I removed the CD from the VM and rebooted, thinking that would be the end of it, but nope:
The EFI shell presented where GRUB should have been
I put the installer CD back and booted in “Rescue Mode”. For some reason, the bootloader installation wasn’t working, so I planned to reinstall it. The autopartition layout for Debian with EFI seems to use /dev/sda2 for the root partition. When you choose this it will see that you have an EFI partition and offer to mount it for you too.
When I went to install the bootloader, I saw another option that I didn’t know about: “Force GRUB installation in removable media path”. In the work I did on live-wrapper I had only ever dealt with this method of booting, I didn’t realise that there were other methods. The reasoning behind this option can be found in detail in Debian bug #746662. I also found mjg59’s blog post from 2011 useful in understanding this.
Suffice is to say that this fixed the booting issue for me in this case. I haven’t investigated this much futher so I can’t be certain of any reproducable steps to this problem, but I did also stumble across this forum post which essentially gives the manual steps that are taken by that Rescue Mode option in order to fix the problem. I think the only reason I hadn’t run into this before now is that the VMs hadn’t been rebooted since their installation.