[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Re: APIC rework
Konrad Rzeszutek Wilk wrote: > On Wed, Nov 18, 2009 at 11:37:51AM +0800, Zhang, Xiantao wrote: >> Jeremy Fitzhardinge wrote: >>> On 11/17/09 06:17, Zhang, Xiantao wrote: >>>> Originally, this patch is target to get rid of ioapic changes in >>>> dom0. Before this patch, GSI irq should be mapped and setup through >>>> dom0 programming ioapic entries, but it depends on using ioapic >>>> logic in dom0. And if we remove ioapic logic from dom0, we need to >>>> find new way how to setup GSI irq. And this patch comes out under >>>> this situation. The idea is from that in Xen the interface >>>> MAP_PIRQ_TYPE_MSI is used to build the pirq and irq mapping for MSI >>>> IRQ for each domain. Since MSI IRQ can be setup through this >>>> hypercall, and I think we also can leverage the interface >>>> MAP_PIRQ_TYPE _GSI to build the mapping for GSI irq. Further >>>> analysis showes that this interface is only used for assigning >>>> devices to HVM domain in qemu, and I think it should be Okay for >>>> dom0 building the mapping between its pirq and irq. One different >>>> thing for GSI irq is that more info should be provided in the call, >>>> since GSI IRQ has different trigger-mode and polarity (originally >>>> it is provided by ioapic write in dom0). Certainly, I also think we >>>> need to document the related info, and if you agree to the change, >>>> I am happy to add it. >>>> >>> >>> I don't think there's any need to overload the existing interface >>> though. If we're adding new functionality then we can add a new >>> interface for it (but with luck we can reuse most of the existing >>> code to implement it). >> >>> If you're already considering a "treat this differently" flag in the >>> argument, then that's a strong pointer that a new interface is >>> warranted. >> >> Agree, and I also don't object to add a similar interface. >> Since this existing interface is only used for hvm domain before, >> and just want to re-use it for dom. > > I am pretty sure it is used for PV domains too. Look in > 'xen_create_msi_irq', which extracts the domain that has a PCI device > for pass-through and on behalf of that domain makes the > MAP_PIRQ_TYPE_MSI call. > > Furthermore, it is also used by Dom0 for MSI devices. We mean the call MAP_PIRQ_TYPE_GSI, not MAP_PIRQ_TYPE_MSI. > What do you mean by 're-use it for dom'? Oh, seems the char "0" is missing, should be dom0. Xiantao _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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