From: Bjorn Helgaas <helgaas@kernel.org>
To: "Tang, CQ" <cq.tang@intel.com>
Cc: linux-pci@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Alexander Gordeev <agordeev@redhat.com>
Subject: Re: Handling MSI-X Vector Shortages
Date: Fri, 15 Jul 2016 17:05:01 -0500 [thread overview]
Message-ID: <20160715220501.GC1706@localhost> (raw)
In-Reply-To: <1D440B9B88E22A4ABEF89F9F1F81BC29490C2138@FMSMSX106.amr.corp.intel.com>
[+cc Christoph, Alexander]
Best to wrap your emails to fit in 70 columns or so.
On Wed, Jun 15, 2016 at 07:03:09PM +0000, Tang, CQ wrote:
> Hi,
> I am writing a driver to deal with MSI-X vector shortage. PCI local bus specification 6.8.3.2 clearly says that, software controlled aliasing can be used to solve the problem, where multiple MSI-X table entries are configured with the same vector.
> pci_enable_msix() call from driver only configure the entries specified in the argument with different vectors. Does Linux provide help function to copy MSI-X table entries? I search the pci/msi source code and don't find an exported function to do that.
I don't think so.
> If there are such function, please tell the function name. if not, can we add such help function?
> Or is driver allowed to access the MSI-X table entries directly, etc, read from one entry (configured by PCI subsystem), and write to another unused entry?
I don't think drivers should fiddle with MSI-X table entries directly.
That sounds like a way to confuse the PCI core. I added Christoph
and Alexander because they're working on similar issues.
Bjorn
prev parent reply other threads:[~2016-07-15 22:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-15 19:03 Handling MSI-X Vector Shortages Tang, CQ
2016-07-15 22:05 ` Bjorn Helgaas [this message]
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