Re: ACPI/UEFI support for Xen/ARM status?

[Elliott Mitchell <ehem+xen@xxxxxxx>]

On Fri, Nov 12, 2021 at 11:00:54PM +0000, Julien Grall wrote:
> On Fri, 12 Nov 2021 at 22:32, Elliott Mitchell <ehem+xen@xxxxxxx> wrote:
> > > My preference is to introduce a per-platform quirk (I believe Stefano was 
> > > happy
> > > with this). The advantage is we could get ACPI support for your board 
> > > hopefully
> > > merged quicker.
> >
> > This could be workable as a temporary workaround.  Longer term I suspect
> > it might well be rather better to *fully* tackle the issue *now*.
> > Otherwise this seems likely to turn into a database of board-specific
> > hacks for hundreds or thousands of devices.
> 
> As usual, you have to find a balance between cost vs benefits.
> 
> If you look at the Device-Tree side, we don' t have many platforms
> requiring quirks.
> In particular, the DMA is so far strictly limited to a single platform (RPI).
> So I would be surprised if we suddenly require tons of quirks when using
> ACPI.

Presently the DMA quirk would be the only consumer, but there will likely
be other consumers later.  Might there be few device-tree quirks due to a
short list of platforms?  Might full ACPI support vastly increase
Xen/ARM's target audience?  (partially ACPI so complex to support so many
varied devices)

I do concede a device-quirk is reasonable for the short-term.  Presently
I don't know where to look for better matching targets, so I'm trapped in
a cave with no light.


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