Messages in this thread | | | Date | Fri, 21 Nov 2014 11:49:05 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: Removal of bus->msi assignment breaks MSI with stacked domains |
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Marc,
On Fri, 21 Nov 2014, Marc Zyngier wrote: > On 21/11/14 01:46, Thomas Gleixner wrote: > > So the real question is: > > > > What is the association level requirement to properly identify the > > irqdomain for a specific device on any given architecture with and > > without IOMMU, interrupt redirection etc. > > > > To be honest: I don't know. > > > > My gut feeling tells me that it's at the device level, but I really > > leave that decision to the experts in that field. > > Given the above requirement (single device associated to DMAR), I can > see two possibilities: > - we represent DMAR as a single PCI bus: feels a bit artificial > - we move the MSI domain to the device, as you suggested. > > The second one seems a lot more attractive to me.
And that's very useful if you want to support MSI on non PCI devices.
> Also, it is not clear to me what is the advantage of getting rid of the > MSI controller. By doing so, we loose an important part of the topology > information (the irq domain is another level of abstraction).
That was probably my misunderstanding of the msi controller. I had the impression it's just there to expose the MSI properties of a device, i.e. a magic wrapper which can be replaced by the MSI irqdomain work.
If that handles other information as well, then it's probably a misnomer to begin with.
Thanks,
tglx
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