Re: [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver.

Jason Gunthorpe
2020-05-03T22:22:39Z

On Fri, May 01, 2020 at 03:31:51PM -0700, Dey, Megha wrote:
> > > This has been my concern reviewing the implementation. IMS needs more
> > > than one in-tree user to validate degrees of freedom in the api. I had
> > > been missing a second "in-tree user" to validate the scope of the
> > > flexibility that was needed.
> >
> > IMS is too narrowly specified.
> >
> > All platforms that support MSI today can support IMS. It is simply a
> > way for the platform to give the driver an addr/data pair that triggers
> > an interrupt when a posted write is performed to that pair.
> >
>
> Well, yes and no. IMS requires interrupt remapping in addition to the
> dynamic nature of IRQ allocation.

You've mentioned remapping a few times, but I really can't understand
why it has anything to do with platform_msi or IMS..

Jason