Re: [PATCH] xen/arm: acpi: Support memory reserve configuration table

[Marc Zyngier <maz@xxxxxxxxxx>]

On Tue, 06 Sep 2022 08:27:47 +0100,
Leo Yan <leo.yan@xxxxxxxxxx> wrote:
> 
> On Tue, Sep 06, 2022 at 09:22:00AM +0200, Ard Biesheuvel wrote:
> 
> [...]
> 
> > > IIUC, you consider the general flow from architecture view, so you prefer
> > > to ask Xen to implement EFI stub to comply the general flow for EFI
> > > booting sequence, right?
> > >
> > > If the conclusion is to change Xen for support EFI stub, then this
> > > would be fine for me and I will hold on and leave Xen developers to work
> > > on it.
> > >
> > 
> > As I mentioned before, proper EFI boot support in Xen would be nice.
> > *However*, I don't think it makes sense to go through all the trouble
> > of implementing that just to shut up a warning that doesn't affect Xen
> > to begin with.
> 
> Another option is we can set a bit for xen feature, so Linux kernel
> can read out the xen feature and make decision if need to reserve
> memory for RD tables based on the new feature bit.  This is somehow
> a solution is to create a general protocol between Xen and Linux kernel.
> 
> How about you think for this?

No. If there is such a bit, it has to be in the GIC architecture. I'm
not putting anything hypervisor-specific into the GIC driver. Others
have tried before you, and they ended up fixing their hypervisor
instead.

Feel free to talk to ARM to get the architecture updated instead.

        M.

-- 
Without deviation from the norm, progress is not possible.