Re: [libvirt] What to do about the qemu "-boot strict" option

On Wed, Nov 27, 2013 at 02:37:02PM +0200, Laine Stump wrote: > Awhile back a bug was filed against libvirt about the inability to completely > exclude a disk from the boot order: > > https://bugzilla.redhat.com/show_bug.cgi?id=888635 > > In short, you can't have a domain that used PXE to boot, but also has an > un-bootable disk device *even if that disk isn't listed in the boot order*, > because if PXE times out (e.g. due to the bridge forwarding delay), the BIOS > will move on to the next target, which will be the unbootable disk device > (again - even though it wasn't given a boot order), and get stuck at a "BOOT > DISK FAILURE, PRESS ANY KEY" message until a user intervenes. > It was obviously beyond the ability of libvirt to fix this (although it can be > worked around by creating a very small disk image with a bootloader that merely > instructs the system to reboot, and placing *that* disk in the boot order just > after the PXE device), so the BZ was closed as CANTFIX. We have a reboot-timeout boot parameter to reboot guest if not found bootable device.

> A couple days ago I noticed that Amos Kong had later actually fixed this > problem in seabios and qemu: > > https://bugzilla.redhat.com/show_bug.cgi?id=888633 > https://bugzilla.redhat.com/show_bug.cgi?id=903204 > > Existing behavior is preserved though, and the new behavior only comes about if > "-boot strict" is specified on the qemu commandline. > It definitely seems desirable to have this ability in libvirt, but I'm almost > of the opinion that this should *always* be the behavior (if you want all > devices to be in the boot order, you can just give all of them (or none of > them, if you're feeling adventurous) a boot order ranking). We leave the default as off just for compatibility with old qemu. For libvirt code, you can always use "strict=on"