Re: [PATCH v2 2/8] ArmPkg: PCD to select conduit for monitor calls

["Ard Biesheuvel" <ardb@kernel.org>]

On Wed, 24 Nov 2021 at 14:05, Leif Lindholm <leif@nuviainc.com> wrote:
>
> On Wed, Nov 24, 2021 at 14:03:51 +0100, Ard Biesheuvel wrote:
> > On Wed, 24 Nov 2021 at 13:07, Leif Lindholm <leif@nuviainc.com> wrote:
> > >
> > > Ard - how does this interact with e.g. ArmVirtPsciResetSystemLib,
> > > which reads its conduit out of the DT passed to it by QEMU?
> > >
> >
> > As long as ArmCallSmc() and ArmCallHvc() continue to exist and behave
> > as before, I don't think those libraries are affected.
>
> Well, I was thinking more that you can now end up with a firmware
> build where the conduit is sometimes dynamically determined, and
> sometimes compile-time determined.
>

There is nothing wrong with that by itself: if you have a DT that
describes this, it makes sense to carry support for both. If the bare
metal you are targetting only ever uses SMC, no need for the discovery
and a PCD is fine.

Question remains whether this PCD could/should be configurable as
dynamic, so we collapse the static/dynamic options into a single PCD
based choice.