[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] [PATCH 1/5] Add MSI support to XEN
>> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx] >> Sent: 2008年3月28日 17:33 >> >> On 28/3/08 09:23, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote: >> >>> I think the reverse. :-) Here IRQ is just a namespace which is >>> allocatable and not bound to platform hard-wired logic. Each MSI >>> just requires one IRQ placeholder to gear to evtchn core with the >>> latter on top of IRQ name- space. However GSI or ISA IRQ more >>> indicates platform attribute which doesn't fit the purpose here, >>> though GSI can be also tweaked in some version of Linux kernel. >> >> I don't understand you. Do you mean *PIRQ* is just a namespace which >> is allocatable? I fully agree with that. I was talking about the >> MAO_IRQ_TYPE_IRQ binding type -- here I believe 'IRQ' does >> refer to a real >> platform resource, but 'IRQ' is not a well-defined >> architectural namespace >> like 'GSI' or 'ISA IRQ'. So the interface should be fixed imo. > > Oh, I jumped in too early. Sorry and you're right. I will change that name. > >> >>> This should work, and may solve the issue Yunhong described in >>> another mail by giving Xen ability to mask device directly upon >>> spurious interrupts. And... seems like less change to Linux code? >>> The only concern is how complex the interface may finally go, >>> and in this case Xen still needs to sync PCI config space access >>> for port I/O style. >> >> Yes, the synchronisation is pretty easy though. We just have >> to add a layer >> of emulation to PV guest accesses to 0xcf8/0xcfc. > > Yes, a small tricky however is, the owner vcpu may be scheduled > out between 0xcf8 and 0xcfc access, when another pcpu is trying > to access PCI config space like masking MSI within do_IRQ... > Maybe Xen need to emulate 0xcf8/0xcfc pair without return to > guest in the middle. :-) Can we add hypercall to combine the two-time access to one? > > Thanks, > Kevin _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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