Failure to boot CDROM with -drive arg

["Daniel P. Berrange" <berrange@redhat.com>]

The following two command lines should be identical from the user's
point of view:

# qemu-kvm -cdrom /home/berrange/boot.iso -boot d -m 500

# qemu-kvm -drive file=/home/berrange/boot.iso,if=ide,media=cdrom,index=2,boot=on -m 500

With the 2nd though, the initial CDROM syslinux loads, but fails to load
the graphical menu, and also fails to boot in text mode fallback:

  'vesamenu.c32: attempted DOS system call"

(See screenshot: https://bugzilla.redhat.com/attachment.cgi?id=311221 )

I've reproduced this with both KVM 65 and 70, on a Fedora 9 host. The CDROM
boot.iso image I'm using here is the Fedora 9  $URL/images/boot.iso from
any standard Fedora install tree.

I can only imagine there's something different in the way extboot sets up
the CPU/pagetables during cdrom boot, but its rather beyond my skills

This was originally reported by a Fedora user here

  https://bugzilla.redhat.com/show_bug.cgi?id=452355

Daniel
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