Re: [Xen-devel] [PATCH 3/6] arm: make it possible to disable the SMMU driver

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 24 Apr 2018, Julien Grall wrote:
> On 04/20/2018 10:39 AM, Jan Beulich wrote:
> > > > > On 19.04.18 at 17:44, <julien.grall@xxxxxxx> wrote:
> > > On 18/04/18 23:15, Stefano Stabellini wrote:
> > > > --- a/xen/drivers/passthrough/Kconfig
> > > > +++ b/xen/drivers/passthrough/Kconfig
> > > > @@ -1,3 +1,5 @@
> > > >       config HAS_PASSTHROUGH
> > > >         bool
> > > > +
> > > > +source "drivers/passthrough/arm/Kconfig"
> > > 
> > > Can't we load arm/Kconfig only when arm is selected? This would avoid
> > > weird option on x86.
> > 
> > How would those options appear for x86, given ...
> > 
> > > > --- /dev/null
> > > > +++ b/xen/drivers/passthrough/arm/Kconfig
> > > > @@ -0,0 +1,7 @@
> > > > +
> > > > +config HAS_SMMUv2
> > > > +       bool "ARM SMMUv2 driver"
> > > > +       default y
> > > > +       depends on ARM
> > 
> > ... this "depends on"? Of course if more options are going to appear here,
> > wrapping the whole file in "if ARM" would be useful anyway, even if only
> > to limit redundancy.

Sorry, I think I am misunderstanding your suggestion. If you are
suggesting:

#if ARM
  config HAS_SMMUv2
  bool "ARM SMMUv2 driver"
  default y
  depends on ARM
#endif

then, this won't work because we are not running the kconfig files
through the preprocessor.


> It will appear when you search for it in the menuconfig. This will look quite
> weird for x86.

Is this a problem? If so, how do we want to fix it? I am OK with
anything, but if it was up to me I would leave it as is (HAS_SMMUv2
comes up on x86 searches on the menu).


> > Otoh, as voiced before in a different context, I'm not convinced we want
> > such single-option Kconfig files, i.e. in the case here the option may
> > better
> > go directly into xen/drivers/passthrough/Kconfig. Splitting files when they
> > grow too large is an option anyway.
> 
> I would be ok with that.

I'll make the change

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