Rather than just picking the first CD (or failing that, HDD) we come
across, if the user has picked a boot device ordering with <boot
order=''>, respect that (and just try to boot the lowest-index device).
Adds two sets of tests to bhyve2xmlargv; 'grub-bootorder' shows that we
pick a user-specified device over the first device in the domain;
'grub-bootorder2' shows that we pick the first (lowest index) device.
This enables booting interactive GRUB menus (e.g. install CDs) with
libvirt-bhyve.
Caveat: A terminal other than the '--console' option to 'virsh start'
(e.g. 'cu -l /dev/nmdm0B -s 115200') must be used to connect to
grub-bhyve because the bhyve loader path is synchronous and must occur
before the VM actually starts.
Changing the bhyveProcessStart logic around to accommodate '--console'
for interactive loader use seems like a significant project and probably
not worth it, if UEFI/BIOS support for bhyve is "coming soon."
We still default to bhyveloader(1) if no explicit bootloader
configuration is supplied in the domain.
If the /domain/bootloader looks like grub-bhyve and the user doesn't
supply /domain/bootloader_args, we make an intelligent guess and try
chainloading the first partition on the disk (or a CD if one exists,
under the assumption that for a VM a CD is likely an install source).
Caveat: Assumes the HDD boots from the msdos1 partition. I think this is
a pretty reasonable assumption for a VM. (DrvBhyve with Bhyveload
already assumes that the first disk should be booted.)
I've tested both HDD and CD boot and they seem to work.