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[Xen-devel] Some questions about Interrupt and event channel about Xen on ARM.

  • To: xen-devel@xxxxxxxxxxxxx
  • From: ììì <supsup5642@xxxxxxxxx>
  • Date: Tue, 27 Jan 2015 16:15:59 +0900 (KST)
  • Delivery-date: Tue, 27 Jan 2015 08:30:39 +0000
  • Importance: normal
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>


I'm studying about Xen 4.4.0 and Xen 4.5.0 on ARM


I have some questions about Interrupt and event channel on ARM. 


In Xen 4.4.X and Xen 4.5.0 (GIC v2), all pirq(physical irq) are go to pcpu0 (physical cpu). After pirq, Xen run in pcpu0 only inject virq(virtual irq) to vcpu0 of Dom0.
I think injection of virtual irq to proper vcpu carry out interrupt load balancing and reducing interrupt latency.
Why dose Xen only route virtual to vcpu0 of Dom0? For only simple??


Xen 4.5.0 support GiC v3. I saw code about GICv3 in Xen 4.5.0.

it seems that GICv3 add some virq interrupt routing interface such as 'GICD_IROUTER_SPI_MODE_ANY' 

and support irq migration. But i know that 'GICv3 Architecture Specification' release specification in later this year.
How can Xen 4.5.0 Developers get GICv3 Information and where can i get GICv3 Information??



In Xen 4.4.0, Xen occur 'GIC_SGI_EVENT_CHECK' sgi interrupt to check event channel. After GIC_SGI_EVENT_CHECK sgi, 'leave_hypervisor_tail' function is executed on return path.

leave_hypervisor_tail function inject virq of event channel. 

But In Xen 4.5.0, After GIC_SGI_EVENT_CHECK sgi, leave_hypervisor_tail dosen't inject virq of event channel.

and There is no virq injection of event channel on return path. 

So I think, to send GIC_SGI_EVENT_CHECK sgi is meaning less in Xen 4.5.0.


Right?? Am i wrong?




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