RE: [Xen-ia64-devel] vIOSAPIC and IRQs delivery

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

Welcome Kenji. 

Thanks,
Kevin

>-----Original Message-----
>From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Kenji
>Kaneshige
>Sent: 2006年3月9日 18:13
>To: Tristan Gingold
>Cc: Luck, Tony; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: Re: [Xen-ia64-devel] vIOSAPIC and IRQs delivery
>
>Hi,
>
>Tristan Gingold wrote:
>> Le Jeudi 09 Mars 2006 01:31, Luck, Tony a écrit :
>>
>>>>BTW, I think it will be *very* hard to find an ia64 platform which can
>>>>share an IRQ line.  Maybe I am wrong but I don't know such a platform :-(
>>>
>>>Hard? No.
>>
>> I'd like to have a vendor name and a platform name!
>
>Fujitsu PRIMEQUEST can have so many (> 512) gsi sources and it
>needs shared IRQ (vector). Note that what I'm talking is not
>sharing IRQ lines but sharing interrupt vector between multiple
>RTEs.
>
>>
>>
>>>Expensive? Yes.
>>>
>>>There are only 255 irqs - minus some that the base kernel steals
>>>for cmc, mca, timer, perfmon, etc.  So any large system with a
>>>few hundred i/o cards _must_ share irqs.  There aren't enough
>>>for one each.
>>
>> I don't agree.  You can have interrupt domains.  See "Intel Itanium
>Processor
>> Family Interrupt Architecture Guide".
>
>As you said, interrupt domains approach is better because
>
>    - Shared IRQ (vector) approach would not work for
>      edge-triggered interrupts including MSIs.
>
>    - Interrupt domains approach would have much better
>      performance
>
>Unfortunately, AFAIK, interrupt domains approach has not be
>implemented for generic ia64-linux kernel yet. It would be
>very nice if it is implemented someday. But I guess we need
>a lot of efforts for it. To tell the truth, I've posted the
>patches for interrupt domains to ia64-linux mailing list
>before, though it contains many TBDs and bugs (maybe).
>Please see the following URL if necessary.
>
>http://marc.theaimsgroup.com/?l=linux-ia64&m=112133320424016&w=2
>
>Thanks,
>Kenji Kaneshige
>
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