Re: [Qemu-devel] [PATCH] Don't use QEMU_VERSION in ATA/ATAPI replies to IDENTIFY cmds

[Jamie Lokier <jamie@shareable.org>]

Glauber Costa wrote:
> On Thu, Sep 11, 2008 at 5:18 AM, Jamie Lokier <jamie@shareable.org> wrote:
> > Marc Bevand wrote:
> >> Consider this scenario: I change the MAC and the host at some point;
> >> no reactivation required. 10 months later I simply upgrade QEMU from
> >> 0.9.0 to 0.9.1 and change nothing else; reactivation is required. This
> >> is not something an enduser would expect.
> >
> > I agree.  (Also I agree with Glauber that the OS is sucky to care, but
> > it does and it's a notable use of QEMU to let you run Windows as a
> > guest so you can run Linux as a host :-)
> 
> My point is that in this case, you _are_ changing hardware. QEMU is a
> piece of hardware anyway.

If that is a hardware change, can we please have an option _not_ to
change the hardware when upgrading QEMU ;-)

> But we can't guarantee that future qemu updates won't change the way
> the O.S. views hardware significantly.

We should.  If upgrading QEMU changes the emulated hardware
significantly, it'll break some guests - not just Windows, but sane
guests with drivers not expecting the hardware to be suddenly different :-)

Significant changes should be accompanied by options, in the same way
that, say, you can select among different NICs, and ought to be able
to select among PIIX3 and PIIX4 etc.

Bug fixes and performance improvements are fine.

-- Jamie