Re: [PATCH v2 1/4] x86: provide an inverted Kconfig control for shim-exclusive mode

["Alejandro Vallejo" <alejandro.vallejo@cloud.com>]

On Fri Jan 17, 2025 at 10:31 AM GMT, Roger Pau Monné wrote:
> On Thu, Jan 16, 2025 at 04:31:46PM -0800, Stefano Stabellini wrote:
> > On Wed, 1 Mar 2023, Jan Beulich wrote:
> > > While we want certain things turned off in shim-exclusive mode, doing
> > > so via "depends on !PV_SHIM_EXCLUSIVE" badly affects allyesconfig: Since
> > > that will turn on PV_SHIM_EXCLUSIVE, other options will be turned off as
> > > a result. Yet allyesconfig wants to enable as much of the functionality
> > > as possible.
> > > 
> > > Retain PV_SHIM_EXCLUSIVE as a prompt-less option such that first of all
> > > C code using it can remain as is. This isn't just for less code churn,
> > > but also because I think that symbol is more logical to use in many
> > > (all?) places.
> > > 
> > > Requested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> > > Signed-off-by: Jan Beulich <jbeulich@suse.com>
> > >
> > > ---
> > > The new Kconfig control's name is up for improvement suggestions, but I
> > > think it's already better than the originally thought of
> > > FULL_HYPERVISOR.
> > 
> > I think the approach in general is OK, maybe we can improve the naming
> > further. What about one of the following?
> > 
> > NO_PV_SHIM_EXCLUSIVE
> > PV_SHIM_NOT_EXCLUSIVE
>
> IMO negated options are confusing, and if possible I think we should
> avoid using them unless strictly necessary.

The problem is that the option is negative in nature. It's asking for
hypervisor without _something_. I do agree with Stefano that shim would be
better in the name. Otherwise readers are forced to play divination tricks.

How about something like:

    SHIMLESS_HYPERVISOR

That's arguably not negated, preserves "shim" in the name and has the correct
polarity for allyesconfig to yield the right thing.

>
> I for example always considered extremely confusing that previous to
> having CONFIG_DEBUG Xen used NDEBUG (so no debug) as a way to signal
> debug vs non-debug builds.
>
> Thanks, Roger.

Cheers,
Alejandro