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Date:   Thu, 23 Apr 2020 16:49:41 -0300
From:   Jason Gunthorpe <jgg@mellanox.com>
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     Dave Jiang <dave.jiang@intel.com>, Vinod Koul <vkoul@kernel.org>,
        Megha Dey <megha.dey@linux.intel.com>, maz@kernel.org,
        Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Jacob jun Pan <jacob.jun.pan@intel.com>,
        "Raj, Ashok" <ashok.raj@intel.com>, Yi L Liu <yi.l.liu@intel.com>,
        Baolu Lu <baolu.lu@intel.com>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        Sanjay K Kumar <sanjay.k.kumar@intel.com>,
        "Luck, Tony" <tony.luck@intel.com>, Jing Lin <jing.lin@intel.com>,
        kwankhede@nvidia.com, eric.auger@redhat.com, parav@mellanox.com,
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        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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Subject: Re: [PATCH RFC 00/15] Add VFIO mediated device support and IMS
 support for the idxd driver.
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On Thu, Apr 23, 2020 at 12:17:50PM -0700, Dan Williams wrote:

> Per Megha's follow-up can you send the details about that other device
> and help clear a path for a device-specific MSI addr/data table
> format. Ever since HMM I've been sensitive, perhaps overly-sensitive,
> to claims about future upstream users. The fact that you have an
> additional use case is golden for pushing this into a common area and
> validating the scope of the proposed API.

I think I said it at plumbers, but yes, we are interested in this, and
would like dynamic MSI-like interrupts available to the driver (what
Intel calls IMS)

It is something easy enough to illustrate with any RDMA device really,
just open a MR against the addr and use RDMA_WRITE to trigger the
data. It should trigger a Linux IRQ. Nothing else should be needed.

Jason