Re: [Qemu-devel] [PATCH 0/2] port over extboot from kvm

[Paul Brook]

On Wednesday 11 November 2009, Anthony Liguori wrote:
> Hannes Reinecke wrote:
> > But why? Why do we have to emulate the entire HBA for the BIOS?
> > The HBA is emulated, too, and just uses the bdrv interface
> > internally anyway.
> > So IMHO it makes far more sense to skip the HBA emulation in
> > the BIOS completely and just use the bdrv interface directly
> > here.
> 
> If you use the bdrv interface (ala extboot), you couldn't boot via scsi
> passthrough.
> 
> VirtualBox implements a paravirtual SCSI bus to allow SCSI boot without
> having to implement a full LSI driver.  That's another way to solve the
> problem.

This has its own issues. How do you prevent the guest enumerating both the 
paravirt and "real" adapters, and getting the same disk twice? If this isn't a 
problem, then surely the user can do this explicitly.

In this case "guest" includes future fancy versions of the BIOS/bootloader.

Paul