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Date:   Wed, 2 Nov 2022 17:54:06 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Davidlohr Bueso <dave@stgolabs.net>
Cc:     Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Ira Weiny <ira.weiny@intel.com>, dave.jiang@intel.com,
        alison.schofield@intel.com, bwidawsk@kernel.org,
        vishal.l.verma@intel.com, a.manzanares@samsung.com,
        linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org,
        Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 1/2] cxl/pci: Add generic MSI-X/MSI irq support
Message-ID: <20221102225406.GA5803@bhelgaas>
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On Wed, Nov 02, 2022 at 10:15:24AM -0700, Davidlohr Bueso wrote:
> On Tue, 25 Oct 2022, Bjorn Helgaas wrote:
> ...

> > The MSI case is ugly because the Interrupt Message Number can change
> > when we set Multiple Message Enable.  Maybe we can separate it out and
> > have a less than optimal solution for this case, like allocating one
> > or two vectors and polling if that's not enough.  I expect most
> > devices will support MSI-X.
> 
> Would only supporting MSI-X be so terrible?

My gut feeling is that polling when MSI-X isn't supported wouldn't be
terrible, but I have no data on how common devices that only support
MSI are.

Bjorn