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RE: [Xen-devel] [PATCH 2/3][RFC] MSI/MSI-X support fordom0/driver domain

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH 2/3][RFC] MSI/MSI-X support fordom0/driver domain
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Mon, 28 May 2007 20:53:58 +0800
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Thread-topic: [Xen-devel] [PATCH 2/3][RFC] MSI/MSI-X support fordom0/driver domain
>From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>Sent: 2007年5月28日 20:41
>On 28/5/07 13:29, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>> I understand your point, and yes that's an easy implementation. My
>> small concern now is just whether it's worthy to pull Xen into resource
>> allocation for which Xen has nothing reference at all. Shouldn't the
>> components to assign device irq better does the allocation based on
>> its own policy? For current stage, HVM domain has device model to
>> provide 'pirq' layout and driver domainU has pciback. Even when later
>> there're other places to assign device irqs, I think it's still 
>> responsibility
>> of that place to construct the pirq name space for domU. For example,
>> how about the simple Xen pirq allocation policy doesn't satisfy the
>> special requirement of that place, like a special prime-number style
>> (just kidding)? If such simple, but no-use from Xen POV, interface
>> doesn't have users now and also may not address all possibilities in
>> the future, do we need that indeed?
>You may be right. I just like to keep the hypervisor interfaces as flexible
>as possible, to avoid unnecessarily baking in assumptions based on their
>initial usage. It's a pretty small issue actually, since we can get the same
>behaviour by dom0 attempting to map onto pirqs from zero upwards until
>finds one that isn't already in use.
> -- Keir

Yep, exactly a small issue. Let's expect Yunhong's next version after 
incorporating your comments. :-)


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