Re: [Xen-devel] How dispatch a vIRQ to all guests in ARM

[Josh Zhao <joshsystem@xxxxxxxxx>]

Hi lan,

Thanks for answering my question. I was imagining that some hardware drivers might be sharing in domains, such as ethernet, SD card. Two more domains may access to the device same time. I thought the same IRQ may be associated with each domain. Now I am thinking that the vIRQs should be dispatched between domains by event channels.  A channel  means one 2 one domain mapping. Each channel is a vIRQ. Am I right?

BTW, I have 2 other questions in this thread:

(1) The tranditional Linux kernel without virtualization is running on SVC mode.  With virtualization,the Linux kernel in DomU is on ARM's SVC mode and the Dom0 is in Hyper Mode?

(2) I am wondering How xen pass memory to domains( Dom0/DomU)?   Are there any key fields associated with memory in domain/vcpu structs, such like Linux kernel 's mm struct?

josh zhao

2013/3/12 Ian Campbell <Ian.Campbell@xxxxxxxxxx>

On Mon, 2013-03-11 at 07:13 +0000, Josh Zhao wrote:
> Hi,
>
> I am reading the code, but I can't understand how an interrupt
> dispatch to all guests?  As code description that do_IRQ()
> -->vgic_vcpu_inject_irq(), but it seems only inject an irq into ONE
> VCPU. Is there a case that one irq registered by many guests?

A single interrupt source (be it physical hardware or a purely software
construct) can only ever be associated with a single domain.

What use case were you imagining where this may not be true?

Ian.

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