[libvirt] [PATCH v2 09/10] docs: Provide a nodedev driver stub documentation
Pavel Hrdina
phrdina at redhat.com
Mon Apr 24 14:07:08 UTC 2017
On Mon, Apr 24, 2017 at 04:04:01PM +0200, Pavel Hrdina wrote:
> On Thu, Apr 20, 2017 at 03:05:59PM +0200, Erik Skultety wrote:
> > There's lot more to document about the nodedev driver, besides PCI and
> > SR-IOV (even this might need to be extended), but let's start small-ish
> > and at least have a page for it linked from the drivers.html.
> >
> > Signed-off-by: Erik Skultety <eskultet at redhat.com>
> > ---
> > docs/drivers.html.in | 6 +-
> > docs/drvnodedev.html.in | 184 ++++++++++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 189 insertions(+), 1 deletion(-)
> > create mode 100644 docs/drvnodedev.html.in
> >
> > diff --git a/docs/drivers.html.in b/docs/drivers.html.in
> > index be7483b9b..61993861e 100644
> > --- a/docs/drivers.html.in
> > +++ b/docs/drivers.html.in
> > @@ -4,7 +4,11 @@
> > <body>
> > <h1>Internal drivers</h1>
> >
> > - <ul id="toc"></ul>
> > + <ul>
> > + <li><a href="#hypervisor">Hypervisor drivers</a></li>
> > + <li><a href="#storage">Storage drivers</a></li>
> > + <li><a href="drvnodedev.html">Node device driver</a></li>
> > + </ul>
> >
> > <p>
> > The libvirt public API delegates its implementation to one or
> > diff --git a/docs/drvnodedev.html.in b/docs/drvnodedev.html.in
> > new file mode 100644
> > index 000000000..ed185c3df
> > --- /dev/null
> > +++ b/docs/drvnodedev.html.in
> > @@ -0,0 +1,184 @@
> > +<?xml version="1.0" encoding="UTF-8"?>
> > +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
> > +<html xmlns="http://www.w3.org/1999/xhtml">
> > + <body>
> > + <h1>Host device management</h1>
> > +
> > + <p>
> > + Libvirt provides management of both physical and virtual host devices
> > + (historically also referred to as node devices) like USB, PCI, SCSI, and
> > + network devices. This also includes various virtualization capabilities
> > + which the aforementioned devices provide for utilization, for example
> > + SR-IOV, NPIV, MDEV, DRM, etc. <br/>
> > + <br/>
>
> You should use </p> and <p> instead of double <br/> if we are using paragraphs.
>
> > + The node device driver provides means to list and show details about host
> > + devices (<code>virsh nodedev-list</code>,
> > + <code>virsh nodedev-dumpxml</code>), which are generic and can be used
> > + with all devices. It also provides means to create and destroy devices
> > + (<code>virsh nodedev-create</code>, <code>virsh nodedev-destroy</code>)
> > + which are meant to be used to create virtual devices, currently only
> > + supported by NPIV
> > + (<a href="http://wiki.libvirt.org/page/NPIV_in_libvirt">more info about NPIV)</a>). <br/>
> > + <br/>
>
> Same here.
>
> > + Devices on the host system are arranged in a tree-like hierarchy, with
> > + the root node being called <code>computer</code>. The node device driver
> > + supports two backends to manage the devices, HAL and udev, with the former
> > + being deprecated in favour of the latter.<br/>
>
> Either remove the single <br/> or replace it with a pair of </p> and <p> to end
> current paragraph and start a new one.
>
> > + The generic format of a host device XML can be seen below.
> > + To identify a device both within the host and the device tree hierarchy,
> > + the following elements are used:
> > + </p>
> > + <dl>
> > + <dt><code>name</code></dt>
> > + <dd>
> > + The device's name will be generated by libvirt using the subsystem,
> > + like pci and the device's sysfs basename.
> > + </dd>
> > + <dt><code>path</code></dt>
> > + <dd>
> > + Fully qualified sysfs path to the device.
> > + </dd>
> > + <dt><code>parent</code></dt>
> > + <dd>
> > + This element identifies the parent node in the device hierarchy. The
> > + value of the element will correspond with the device parent's
> > + <code>name</code> element or <code>computer</code> if the device does
> > + not have any parent.
> > + </dd>
> > + <dt><code>driver</code></dt>
> > + <dd>
> > + This elements reports the driver in use for this device. The presence
> > + of this element in the output XML depends on whether the underlying
> > + device manager (most likely udev) exposes information about the
> > + driver.
> > + </dd>
> > + <dt><code>capability</code></dt>
> > + <dd>
> > + Describes the device in terms of feature support. The element has one
> > + mandatory attribute <code>type</code> the value of which determines
> > + the type of the device. Currently recognized values for the attribute
> > + are:
> > + <code>system</code>,
> > + <code>pci</code>,
> > + <code>usb</code>,
> > + <code>usb_device</code>,
> > + <code>net</code>,
> > + <code>scsi</code>,
> > + <code>scsi_host</code> (<span class="since">Since 0.4.7</span>),
> > + <code>fc_host</code>,
> > + <code>vports</code>,
> > + <code>scsi_target</code> (<span class="since">Since 0.7.3</span>),
> > + <code>storage</code> (<span class="since">Since 1.0.4</span>),
> > + <code>scsi_generic</code> (<span class="since">Since 1.0.7</span>),
> > + <code>drm</code> (<span class="since">Since 3.1.0</span>), and
> > + <code>mdev</code> (<span class="since">Since 3.2.0</span>).
> > + This element can be nested in which case it further specifies a
> > + device's capability. Refer to specific device types to see more values
> > + for the <code>type</code> attribute which are exclusive.
> > + </dd>
> > + </dl>
> > +
> > + <h2>Basic structure of a node device</h2>
> > + <pre>
> > +<device>
> > + <name>pci_0000_00_17_0</name>
> > + <path>/sys/devices/pci0000:00/0000:00:17.0</path>
> > + <parent>computer</parent>
> > + <driver>
> > + <name>ahci</name>
> > + </driver>
> > + <capability type='pci'>
> > +...
> > + </capability>
> > +</device></pre>
> > +
> > + <ul id="toc"/>
> > +
> > + <h2><a name="PCI">PCI host devices</a></h2>
> > + <dl>
> > + <dt><code>capability</code></dt>
> > + <dd>
> > + When used as top level element, the supported values for the
> > + <code>type</code> attribute are <code>pci</code> and
> > + <code>phys_function</code> (see <a href="#SRIOVCap">SR-IOV below</a>).
> > + </dd>
> > + </dl>
> > + <pre>
> > +<device>
> > + <name>pci_0000_04_00_1</name>
> > + <path>/sys/devices/pci0000:00/0000:00:06.0/0000:04:00.1</path>
> > + <parent>pci_0000_00_06_0</parent>
> > + <driver>
> > + <name>igb</name>
> > + </driver>
> > + <capability type='pci'>
> > + <domain>0</domain>
> > + <bus>4</bus>
> > + <slot>0</slot>
> > + <function>1</function>
> > + <product id='0x10c9'>82576 Gigabit Network Connection</product>
> > + <vendor id='0x8086'>Intel Corporation</vendor>
> > + <iommuGroup number='15'>
> > + <address domain='0x0000' bus='0x04' slot='0x00' function='0x1'/>
> > + </iommuGroup>
> > + <numa node='0'/>
> > + <pci-express>
> > + <link validity='cap' port='1' speed='2.5' width='2'/>
> > + <link validity='sta' speed='2.5' width='2'/>
> > + </pci-express>
> > + </capability>
> > +</device></pre>
> > +
> > + <p>
> > + The XML format for a PCI device stays the same for any further
> > + capabilities it supports, a single nested <code><capability></code>
> > + element will be included for each capability the device supports.
> > + </p>
> > +
> > + <h3><a name="SRIOVCap">SR-IOV capability</a></h3>
> > + <p>
> > + Single root input/output virtualization (SR-IOV) allows sharing of the
> > + PCIe resources by multiple virtual environments. That is achieved by
> > + slicing up a single full-featured physical resource called physical
> > + function (PF) into multiple devices called virtual functions (VFs) sharing
> > + their configuration with the underlying PF. Despite the SR-IOV
> > + specification, the amount of VFs that can be created on a PF varies among
> > + manufacturers.<br/>
> > + <br/>
>
> Replace double <br/> with </p> and <p>.
>
> > + Suppose the NIC <a href="#PCI">above</a> was also SR-IOV capable, it would
> > + also include a nested
> > + <code><capability></code> element enumerating all virtual
> > + functions available on the physical device (physical port) like in the
> > + example below.
> > + </p>
> > +
> > + <pre>
> > +<capability type='pci'>
> > +...
> > + <capability type='virt_functions' maxCount='7'>
> > + <address domain='0x0000' bus='0x04' slot='0x10' function='0x1'/>
> > + <address domain='0x0000' bus='0x04' slot='0x10' function='0x3'/>
> > + <address domain='0x0000' bus='0x04' slot='0x10' function='0x5'/>
> > + <address domain='0x0000' bus='0x04' slot='0x10' function='0x7'/>
> > + <address domain='0x0000' bus='0x04' slot='0x11' function='0x1'/>
> > + <address domain='0x0000' bus='0x04' slot='0x11' function='0x3'/>
> > + <address domain='0x0000' bus='0x04' slot='0x11' function='0x5'/>
> > + </capability>
> > +...
> > +</capability></pre>
> > + <p>
> > + A SR-IOV child device on the other hand, would then report its top level
> > + capability type as a physical function instead:
> > + </p>
> > +
> > + <pre>
> > +<device>
> > +...
> > + <capability type='phys_function'>
> > + <address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
> > + </capability>
> > +...
> > +<device></pre>
> > +
> > + </body>
> > +</html>
> > --
> > 2.12.2
>
> I'm not a native speaker but the text makes sense and having something is
> definitely better than having no documentation at all.
>
> ACK
>
> Pavel
If you remove all MDEV references you can push it right away.
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