Re: [PATCH-for-9.0 07/10] sysemu/xen-mapcache: Check Xen availability with CONFIG_XEN_IS_POSSIBLE

[Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>]

Cc'ing Paolo

On 14/11/23 13:25, Philippe Mathieu-Daudé wrote:
> On 13/11/23 20:52, David Woodhouse wrote:
> > On Mon, 2023-11-13 at 16:21 +0100, Philippe Mathieu-Daudé wrote:
> > > "sysemu/xen.h" defines CONFIG_XEN_IS_POSSIBLE as a target-agnostic
> > > version of CONFIG_XEN. Use it in order to use "sysemu/xen-mapcache.h"
> > > in target-agnostic files.
> > >
> > > Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
> > Noting that CONFIG_XEN_IS_POSSIBLE is for Xen accelerator support, and
> > may not be set in all cases when we're hosting Xen-compatible guests,
> As is CONFIG_XEN.
Actually we have:

- host Xen support
  . CONFIG_XEN_BACKEND

- QEMU Xen accelerator
  . CONFIG_XEN

- HW models
  . CONFIG_XEN (old / generic models)
  . CONFIG_XEN_BUS
  . XEN_IGD_PASSTHROUGH (PCI stuff)
  . CONFIG_XEN_EMU (Xen on KVM)

Paolo, David, is that correct?

When can we have CONFIG_XEN without CONFIG_XEN_BACKEND
(and vice-et-versa)?

So for clarity CONFIG_XEN could be split as:
 - CONFIG_ACCEL_XEN
 - CONFIG_XEN_MACHINE_FV (Fully-virtualized)
 - CONFIG_XEN_MACHINE_PV (Para-virtualized)

> Maybe be worth renaming CONFIG_ACCEL_XEN if you think we need
> guest hw specific CONFIG_foo_XEN variables.
>
> > Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> Thanks!