Re: [PATCH v3 2/5] xen/arm: dom0less: Add trap-unmapped-accesses

["Edgar E. Iglesias" <edgar.iglesias@amd.com>]

On Mon, Jun 02, 2025 at 03:57:28PM -0700, Stefano Stabellini wrote:
> On Mon, 2 Jun 2025, Julien Grall wrote:
> > Hi,
> > 
> > On 02/06/2025 23:36, Stefano Stabellini wrote:
> > > On Fri, 30 May 2025, Edgar E. Iglesias wrote:
> > > > From: "Edgar E. Iglesias" <edgar.iglesias@amd.com>
> > > > 
> > > > Add the trap-unmapped-accesses per-domain fdt property.
> > > > 
> > > > Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
> > > > ---
> > > >   docs/misc/arm/device-tree/booting.txt | 10 ++++++++++
> > > >   xen/arch/arm/dom0less-build.c         |  9 ++++++++-
> > > >   2 files changed, 18 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/docs/misc/arm/device-tree/booting.txt
> > > > b/docs/misc/arm/device-tree/booting.txt
> > > > index 59fa96a82e..9add6440de 100644
> > > > --- a/docs/misc/arm/device-tree/booting.txt
> > > > +++ b/docs/misc/arm/device-tree/booting.txt
> > > > @@ -225,6 +225,16 @@ with the following properties:
> > > >       option is provided with a non zero value, but the platform doesn't
> > > > support
> > > >       SVE.
> > > >   +- trap-unmapped-accesses
> > > > +
> > > > +    Optional. An integer that configures handling of accesses to unmapped
> > > > +    address ranges.
> > > > +    If set to 0, guest accesses will read all bits as ones, e.g
> > > > 0xFFFFFFFF
> > > > +    for a 32bit access and writes will be ignored.
> > > > +    If set to 1, guest accesses will trap.
> > > > +
> > > > +    This option is only implemented for ARM where the default is 1.
> > > 
> > > Please expand it to: "This option is only implemented for ARM where the
> > > default is 1 when trap-unmapped-accesses is absent."
> > 
> > I am confused. The document is part of "docs/misc/arm" and some options like
> > "sve" are Arm specific. We don't mention this is Arm only because the
> > documention is Arm specific.
> > 
> > I know that RISC-V is starting to share the bindings. So really (part of) the
> > documentation should be moved to common. Until then, I think it is misleading
> > to add "is only implemented for ARM".
> 
> Yes you are right. Maybe Oleksii or Alejandro can fix this, moving this
> file to common.
> 
> For this smaller patch series, I would remove the "is only implemented
> for ARM".

Thanks, I've changed that line to:
"The default is 1 when trap-unmapped-accesses is absent."

Cheers,
Edgar