Re: [PATCH RFC v2 02/18] irq/dev-msi: Add support for a new DEV_MSI irq domain

[Dey, Megha]

Hi Thomas,

On 8/11/2020 2:53 AM, Thomas Gleixner wrote:
> Thomas Gleixner <tglx@xxxxxxxxxxxxx> writes:
>
> CC+: XEN folks
>
> > Thomas Gleixner <tglx@xxxxxxxxxxxxx> writes:
> > > The infrastructure itself is not more than a thin wrapper around the
> > > existing msi domain infrastructure and might even share code with
> > > platform-msi.
> > And the annoying fact that you need XEN support which opens another can
> > of worms...

hmm I am not sure why we need Xen support... are you referring to idxd 
using xen?

> which needs some real cleanup first.
>
> x86 still does not associate the irq domain to devices at device
> discovery time, i.e. the device::msi_domain pointer is never populated.
>
> So to support this new fangled device MSI stuff we'd need yet more
> x86/xen specific arch_*msi_irqs() indirection and hackery, which is not
> going to happen.
>
> The right thing to do is to convert XEN MSI support over to proper irq
> domains. This allows to populate device::msi_domain which makes a lot of
> things simpler and also more consistent.

do you think this cleanup is to be a precursor to my patches? I could 
look into it but I am not familiar with the background of Xen

and this stuff. Can you please provide further guidance on where to look?

> Thanks,
>
>          tglx