Messages in this thread | | | Subject | Re: [PATCH 2/3] arm64: dts: add the Alpine v2 EVP | From | Marc Zyngier <> | Date | Tue, 9 Feb 2016 10:42:47 +0000 |
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On 09/02/16 10:13, Tsahee Zidenberg wrote: > On 9 February 2016 at 11:30, Marc Zyngier <marc.zyngier@arm.com> wrote: >> >> 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 >> > By "disabling lecgacy support in early boot" I don't just mean that > ARE bit will be set, but it will actually be RAO/WI. There will be no > way for SW to enable it and use these registers (which, sadly, means > that there will be no way to enable gicv2 virtualization). If you > insist - I will dig up the supposed location of GICV and GICH - yet it > will be both untested and entirely unusable.
That's quite sad indeed. You are pointlessly breaking existing software. But hey, that's your choice. At that point, I can't be bothered to care.
> We will add an entry for the maintenance interrupt, as it really can > be used by future configurations.
Well, at least you'll be able to run GICv3 guests, assuming everything else is usable.
M. -- Jazz is not dead. It just smells funny...
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