[PATCH] doc/dmadevs: add note clarifying naming of idxd devices

[Bruce Richardson <bruce.richardson@intel.com>]

Since the test-dma-perf application identifies devices by name, include
in the idxd driver documentation a note on device naming when vfio-pci.
See also discussion in bugzilla[1].

[1] https://bugs.dpdk.org/show_bug.cgi?id=1268

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 doc/guides/dmadevs/idxd.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/doc/guides/dmadevs/idxd.rst b/doc/guides/dmadevs/idxd.rst
index ea101031bf..a9a788ac56 100644
--- a/doc/guides/dmadevs/idxd.rst
+++ b/doc/guides/dmadevs/idxd.rst
@@ -123,6 +123,13 @@ For example::
 
 	$ dpdk-devbind.py -b vfio-pci 6a:01.0
 
+.. note::
+
+  Since each individual queue on the HW device is its own separate dmadev instance,
+  the internal DMA device name includes the HW queue id as a suffix on the PCI id.
+  The above device when used by a DPDK application will be accessible via dmadevs with names:
+  ``0000:6a:01.0-q0``, ``00006a:01.0-q1``, etc.
+
 Device Probing and Initialization
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-- 
2.39.2