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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

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@xxxxxxx>
> > > 
> > > Add the trap-unmapped-accesses per-domain fdt property.
> > > 
> > > Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>
> > > ---
> > >   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".


> BTW, the spelling for should be "Arm" ;).

:-)