Re: [Xen-devel] [PATCH RFC 16/35] ARM64 / ACPI: Parse GTDT to initialize timer

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2015-02-05 at 14:51 +0000, Stefano Stabellini wrote:
> On Thu, 5 Feb 2015, Ian Campbell wrote:
> > On Wed, 2015-02-04 at 21:51 +0000, Julien Grall wrote:
> > > > +    res = platform_init_time();
> > > 
> > > The platform code is DT-centrict.
> > 
> > This is an interesting point. Given the stated goals and reasons for
> > having ACPI on ARM it seems to me that in general nothing under
> > xen/arch/arm/platforms/* should ever be needed, and certainly not things
> > like platform time init which we should insist have been setup correctly
> > by the platform.
> 
> At the moment I don't think that ACPI on ARM is in the state where we
> can get away without anything under platforms.

That might be true, but given that ACPI is supposed to make this stuff
go away I want it to be harder to workaround something in Xen than it
would be to just fix the firmware, so we don't accumulate crappy hacks
while ACPI is immature.

Which means the barrier for getting such things into Xen needs to be
pretty darn high IMHO.

> > It's possible that we might need some concept of ACPI quirks at some
> > point, but lets have a simple rule for now:
> > 
> >       * The initial set of core ACPI patches for Xen should not ever
> >         call into any platform specific code.
> 
> I think that is a good rule for the initial implementation.
> If/When we need platform files on acpi systems, we might want to
> introduce a new separate struct platform_desc for them anyway.

Yeah, I don't think the same struct would make sense.

Ian.


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