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SubjectRe: [PATCH 2/3] arm64: dts: add the Alpine v2 EVP
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On 09/02/16 09:14, Tsahee Zidenberg wrote:
>
>
> On 9 February 2016 at 11:09, Marc Zyngier <marc.zyngier@arm.com
> <mailto:marc.zyngier@arm.com>> wrote:
>
> On 09/02/16 09:01, Antoine Tenart wrote:
> > On Tue, Feb 09, 2016 at 09:56:33AM +0100, Antoine Tenart wrote:
> >> Hi Marc,
> >>
> >> On Mon, Feb 08, 2016 at 03:29:33PM +0000, Marc Zyngier wrote:
> >>> On 08/02/16 09:11, Antoine Tenart wrote:
> >>>
> >>>> + gic: gic@f0100000 {
> >>>> + compatible = "arm,gic-v3";
> >>>> + reg = <0x0 0xf0200000 0x0 0x10000>, /* GIC Dist */
> >>>> + <0x0 0xf0280000 0x0 0x200000>, /* GICR */
> >>>> + <0x0 0xf0100000 0x0 0x2000>; /* GICC */
> >>>> + interrupt-controller;
> >>>> + #interrupt-cells = <3>;
> >>>> + };
> >>>
> >>> Something is wrong here. Either you are missing GICH and GICV (assuming
> >>> you have legacy support), or you have an extra GICC region (which
> >>> doesn't make sense on its own).
> >>
> >> I'll add the missing regions.
> >
> > Hmm, in fact the GICC region shouldn't be there. I'll make some tests
> > and remove it.
>
> If you have a GICv3 with legacy support, you will probably have GICC,
> GICH and GICV. Linux itself will only use GICD and GICR, but it needs at
> least GICV to be able to virtualize GICv2 guests. And GICV is not
> allowed to exist without GICC and GICH, so I really recommend that you
> keep GICC around.
>
>
> We use the GIC without legacy support (we disable it in early boot
> stages), so I think removing the GICC region is the better solution.

Disabling legacy support doesn't mean that:
- the HW isn't present
- the associated regions are not useful

Here, we describe the HW, not the usage you make of it.

And unless you think that having working virtualization is completely
useless, I strongly suggest that you properly document the HW in the
device tree.

Thanks,

M.
--
Jazz is not dead. It just smells funny...

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