[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH v1 10/10] xen/arm: GICv3 device tree parsing
On 03/25/2014 12:33 PM, Julien Grall wrote: > On 03/25/2014 11:04 AM, Stefano Stabellini wrote: >> On Mon, 24 Mar 2014, Julien Grall wrote: >>> Hi Stefano, >>> >>> On 24/03/14 17:34, Stefano Stabellini wrote: >>>> I think that for Dom0 we have to use vgic_v3, because it doesn't only >>>> give you support for more vcpus but also MSI and MSI-X delivery. >>> >>> Right. >>> >>>> >>>> For DomUs it might be important to support vgic_v2 on gicv3 hardware, >>>> however I wouldn't want to defer the decision to the user (i.e. >>>> introduce yet another VM config option), if not for debugging. >>>> >>>> Would it be possible to advirtise both gicv2 and gicv3 on device tree? >>>> What would the guest kernel do in that case? >>> >>> Linux will try to load both GICv2 and GICv3 drivers. In any case I don't >>> think >>> it's a solution because: >>> - you don't know how the kernel will react >>> - how will you choose which backend to use? >>> >>>> Otherwise we could default to vgic_v2 if vcpus <= 8 and vgic_v3 if >>>> vcpus > 8. >>> >>> What about kernel which only support GICv3 and have less than 8 VCPUS? >>> What about of device (MSI, ...) passthrough with this kind of kernel? >>> >>> I think we need to have a VM config option in this specific case. >> >> Having a VM config option is OK, but it should be the last resort for >> people doing something very uncommon. >> >> GICv3 support in Linux and distros is probably going to be widespread >> soon, so we might not have to worry about it though. > > I don't think GICv3 will supported in 3.15. The current series doesn't > support GICv3 on 32 bits > (http://www.spinics.net/lists/arm-kernel/msg317028.html). > > But, I'm more worry about other OS than Linux (e.g FreeRTOS, *BSD,...) > which may not support GICv2 before a while. I should have write GICv3. -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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