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doc: add documentation for uio-hv-generic 

Update UIO documentation to include basic information about
uio_hv_generic.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Stephen Hemminger 2016-10-17 12:33:19 -07:00 committed by Jonathan Corbet
parent 5ac9baf47a
commit a164a8a663
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Documentation/DocBook/uio-howto.tmpl
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@ -45,6 +45,13 @@ GPL version 2.
</abstract>
<revhistory>
<revision>
<revnumber>0.10</revnumber>
<date>2016-10-17</date>
<authorinitials>sch</authorinitials>
<revremark>Added generic hyperv driver
</revremark>
</revision>
<revision>
<revnumber>0.9</revnumber>
<date>2009-07-16</date>
@ -1033,6 +1040,61 @@ int main()
</chapter>
<chapter id="uio_hv_generic" xreflabel="Using Generic driver for Hyper-V VMBUS">
<?dbhtml filename="uio_hv_generic.html"?>
<title>Generic Hyper-V UIO driver</title>
<para>
The generic driver is a kernel module named uio_hv_generic.
It supports devices on the Hyper-V VMBus similar to uio_pci_generic
on PCI bus.
</para>
<sect1 id="uio_hv_generic_binding">
<title>Making the driver recognize the device</title>
<para>
Since the driver does not declare any device GUID's, it will not get loaded
automatically and will not automatically bind to any devices, you must load it
and allocate id to the driver yourself. For example, to use the network device
GUID:
<programlisting>
modprobe uio_hv_generic
echo &quot;f8615163-df3e-46c5-913f-f2d2f965ed0e&quot; &gt; /sys/bus/vmbus/drivers/uio_hv_generic/new_id
</programlisting>
</para>
<para>
If there already is a hardware specific kernel driver for the device, the
generic driver still won't bind to it, in this case if you want to use the
generic driver (why would you?) you'll have to manually unbind the hardware
specific driver and bind the generic driver, like this:
<programlisting>
echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 &gt; /sys/bus/vmbus/drivers/hv_netvsc/unbind
echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 &gt; /sys/bus/vmbus/drivers/uio_hv_generic/bind
</programlisting>
</para>
<para>
You can verify that the device has been bound to the driver
by looking for it in sysfs, for example like the following:
<programlisting>
ls -l /sys/bus/vmbus/devices/vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver
</programlisting>
Which if successful should print
<programlisting>
.../vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver -&gt; ../../../bus/vmbus/drivers/uio_hv_generic
</programlisting>
</para>
</sect1>
<sect1 id="uio_hv_generic_internals">
<title>Things to know about uio_hv_generic</title>
<para>
On each interrupt, uio_hv_generic sets the Interrupt Disable bit.
This prevents the device from generating further interrupts
until the bit is cleared. The userspace driver should clear this
bit before blocking and waiting for more interrupts.
</para>
</sect1>
</chapter>
<appendix id="app1">
<title>Further information</title>
<itemizedlist>