Bug#599200: base-installer: Install amd64 kernel on i686 kvm guest - and fail to boot

[lsorense@csclub.uwaterloo.ca (Lennart Sorensen)]

On Tue, Oct 05, 2010 at 11:07:15PM +0200, Petter Reinholdtsen wrote:
> affects 599200 qemu-kvm
> thanks
> 
> [Lennart Sorensen]
> > The 'lm' flag means this system has 64bit support.  If in fact it
> > doesn't, then the VM is broken.  The installer did the right thing
> > based on the CPU feature flags.
> 
> Assuming this is true, I suggest two things are done to make sure d-i
> work on 32-bits kvm guests on a lenny based kvm host.
> 
>  (1) base-installer is changed to detect 32-bits kvms and to not
>      propose amd64 kernels in this situation.  Not quite sure how to
>      detect 32-bit kvms.
> 
>  (2) a bug is repoted against some kvm related package, to try to get
>      it to stop listing the lm CPU flag for 32-bit kvm guests.  Not
>      quite sure which package it should be reported against.  Perhaps
>      qemu-kvm?
> 
> I've asked the kvm maintainer to provide input in this bug, to see if
> we can figure out a good way to solve it.

I suspect if you run kvm with the -cpu option you can specify what you
desire.  I believe the default is to simply match whatever the host has,
so if the host has a 64bit cpu, then the guest will too.

# kvm -cpu ?
x86           qemu64
x86           phenom
x86         core2duo
x86            kvm64
x86           qemu32
x86          coreduo
x86              486
x86          pentium
x86         pentium2
x86         pentium3
x86           athlon
x86             n270

So if you say you want a pentium3, then you should not have any 64bit
support.  The coreduo probably won't either.

I think the first 4 have 64bit support and the rest do not.

-- 
Len Sorensen