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

[Julien Grall <julien@xxxxxxx>]

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

Cheers,

--
Julien Grall