Re: can't boot dom0

[Chris Bainbridge <chris.bainbridge@gmail.com>]

On 05/10/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:
>
> On 5 Oct 2005, at 19:32, Chris Bainbridge wrote:
>
> > Ah-ha! So it looks like you need CONFIG_X86_UP_IOAPIC or SMP to get it
> > working.
> >
> > Bug 1) xen with non apic kernel is broken
> > Bug 2) compile error with CONFIG_PCI_MSI
>
> Trying to boot an SMP system with a non-APIC domain0 is a recipe for
> disaster. We depend an awful lot on domain0 to get interrupt routing
> correct. If Xen has booted an SMP system, probed IO-APICs and so on,
> domain0 needs to have the same world view.
>
> The 'bug' is really that we don't make it harder for people to shoot
> themselves in the foot in their configuration. Possibly forcing the
> APIC options is the way to go, or at least indicate that setting them
> to N is DANGEROUS.

In my case "SMP" was just uniprocessor hyperthreading, not really SMP,
so I expected it to work. It's a non-obvious error that will trip up a
lot of people, I'd recommend forcing it, or detecting the
hypervisor/kernel SMP mismatch at boottime and printing a big warning.