On Fri, Oct 20, 2023 at 02:25:35PM +0100, Andrew Cooper wrote: > On 20/10/2023 11:29 am, David Woodhouse wrote: > > On Fri, 2023-10-20 at 11:14 +0100, Andrew Cooper wrote: > >> On 19/10/2023 5:21 pm, David Woodhouse wrote: > >>> From: David Woodhouse <d...@amazon.co.uk> > >>> > >>> In shim mode there is no hardware_domain. Dereferencing the pointer > >>> doesn't end well. > >>> > >>> Signed-off-by: David Woodhouse <d...@amazon.co.uk> > >>> --- > >>> This is about as far as I got in my abortive attempt to use the PV shim > >>> without an actual PV console being provided by the HVM hosting > >>> environment. It still doesn't pass the guest's console through to > >>> serial; that only seems to shim to an actual PV console. > >> There's no such thing as a Xen VM without a PV console. > > Huh? There are literally millions of them. > > I'm very prepared to believe there are millions which don't overtly > malfunction when you don't fill in the HVM Params. > > Which is very different from saying "there's a way in the Xen guest ABI > to express 'you don't have a PV console' ".
FWIW, Linux assumes that either the console page or the event channel being 0 implies no console available [0], so I guess that's the ABI now. Roger. [0] https://elixir.bootlin.com/linux/latest/source/drivers/tty/hvc/hvc_xen.c#L258
