Re: [PATCH V5 04/22] xen/ioreq: Make x86's IOREQ feature common

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 28 Jan 2021, Oleksandr wrote:
> On 28.01.21 13:21, Jan Beulich wrote:
> > On 28.01.2021 12:01, Oleksandr wrote:
> > > On 27.01.21 22:46, Stefano Stabellini wrote:
> > > > On Wed, 27 Jan 2021, Oleksandr wrote:
> > > > > Thank you. I got a request to make a possibility for user to select
> > > > > IOREQ via
> > > > > the menuconfig on Arm. Saying tech preview do you mean that I also
> > > > > need to put
> > > > > it under CONFIG_EXPERT on Arm?
> > > > Normally I would say that unless it actually takes an expert to enable
> > > > the feature, it is better to make it depend on CONFIG_UNSUPPORTED [1].
> > > > 
> > > > However, in this case, it might actually take an expert :-)
> > > > Additional patches are still required to enable the feature at the
> > > > toolstack level, and also the user needs to build a userspace ioreq
> > > > server. So in this case I am fine either way. I'll leave it up to you
> > > > and Julien to pick the best one.
> > > > 
> > > > Either way, please add "(EXPERT)" or "(UNSUPPORTED)" in the one-line
> > > > kconfig description for ARM if possible.
> > > > 
> > > > 
> > > > [1] https://marc.info/?l=xen-devel&m=161168780401884
> > > Thank you for the explanation, personally I would prefer EXPERT, but...
> > > 
> > > It would be really nice if we could agreed regarding that *common*
> > > Kconfig option before I submit V6 (which would probably avoid me to send
> > > V7 I hope).
> > > 
> > > Now I see it as following (please note, it is a subject for new patch in
> > > this series, which should come last):
> > > 
> > > +++ b/xen/common/Kconfig
> > > @@ -137,7 +137,13 @@ config HYPFS_CONFIG
> > >             want to hide the .config contents from dom0.
> > > 
> > >    config IOREQ_SERVER
> > > -       bool
> > > +       bool "IOREQ support" if EXPERT || X86
> > This would make the prompt visible for x86, which we don't
> > want.
> 
> Hmm, I missed that point.
> 
> 
> > But I guess Stefano was anyway after ...
> > 
> > > +       default X86
> > > +       depends on HVM
> > > +       ---help---
> > > +         Enables generic mechanism for providing emulated devices to
> > > the guests.
> > > +
> > > +         If unsure, say Y.
> >   config IOREQ_SERVER
> >         bool "IOREQ support (EXPERT)" if EXPERT && !X86
> >         default X86
> >         depends on HVM
> > 
> > As the prompt should be invisible this way on x86, the (EXPERT)
> > doesn't need further qualifying, except maybe in the help text
> > (just to avoid this being taken as a possible mistake).
> 
> Yes, this works as my initial version *but* is invisible on x86,
> 
> what is more that indeed the *EXPERT* tag for IOREQ on x86 will look quite
> odd...
> 
> Perfect, thank you.

Yep, perfect