[PATCH 6/8] docs: Convert 'pci-hotplug' page to rST
Peter Krempa
pkrempa at redhat.com
Thu Mar 10 15:51:28 UTC 2022
One internal reference was modified to work properly.
Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
docs/meson.build | 2 +-
docs/pci-hotplug.html.in | 185 ---------------------------------------
docs/pci-hotplug.rst | 146 ++++++++++++++++++++++++++++++
3 files changed, 147 insertions(+), 186 deletions(-)
delete mode 100644 docs/pci-hotplug.html.in
create mode 100644 docs/pci-hotplug.rst
diff --git a/docs/meson.build b/docs/meson.build
index 3bdea1407d..cdf78a04b4 100644
--- a/docs/meson.build
+++ b/docs/meson.build
@@ -51,7 +51,6 @@ docs_html_in_files = [
'internals',
'java',
'logging',
- 'pci-hotplug',
'php',
'python',
'remote',
@@ -104,6 +103,7 @@ docs_rst_files = [
'newreposetup',
'nss',
'pci-addresses',
+ 'pci-hotplug',
'platforms',
'programming-languages',
'securityprocess',
diff --git a/docs/pci-hotplug.html.in b/docs/pci-hotplug.html.in
deleted file mode 100644
index d61af1930e..0000000000
--- a/docs/pci-hotplug.html.in
+++ /dev/null
@@ -1,185 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE html>
-<html xmlns="http://www.w3.org/1999/xhtml">
- <body>
- <h1>PCI topology and hotplug</h1>
-
- <ul id="toc"></ul>
-
- <p>
- Perhaps surprisingly, most libvirt guests support only limited PCI
- device hotplug out of the box, or even none at all.
- </p>
- <p>
- The reason for this apparent limitation is the fact that each
- hotplugged PCI device might require additional PCI controllers to
- be added to the guest. Since most PCI controllers can't be
- hotplugged, they need to be added before the guest is started;
- however, libvirt has no way of knowing in advance how many devices
- will be hotplugged during the guest's lifetime, thus making it
- impossible to automatically provide the right amount of PCI
- controllers: any arbitrary number would end up being too big
- for some users, and too small for others.
- </p>
- <p>
- Ultimately, the user is the only one who knows how much the guest
- will need to grow dynamically, so the responsibility of planning
- a suitable PCI topology in advance falls on them.
- </p>
- <p>
- This document aims at providing all the information needed to
- successfully plan the PCI topology of a guest. Note that the
- details can vary a lot between architectures and even machine
- types, hence the way it's organized.
- </p>
-
- <h2><a id="x86_64">x86_64 architecture</a></h2>
-
- <h3><a id="x86_64-q35">q35 machine type</a></h3>
-
- <p>
- This is a PCI Express native machine type. The default PCI topology
- looks like
- </p>
-
-<pre>
-<controller type='pci' index='0' model='pcie-root'/>
-<controller type='pci' index='1' model='pcie-root-port'>
- <model name='pcie-root-port'/>
- <target chassis='1' port='0x10'/>
- <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
-</controller></pre>
-
- <p>
- and supports hotplugging a single PCI Express device, either
- emulated or assigned from the host.
- </p>
- <p>
- If you have a very specific use case, such as the appliances
- used by <a href="https://libguestfs.org/">libguestfs</a> behind
- the scenes to access disk images, and this automatically-added
- <code>pcie-root-port</code> controller ends up being a nuisance,
- you can prevent libvirt from adding it by manually managing PCI
- controllers and addresses according to your needs.
- </p>
- <p>
- Slots on the <code>pcie-root</code> controller do not support
- hotplug, so the device will be hotplugged into the
- <code>pcie-root-port</code> controller. If you plan to hotplug
- more than a single PCI Express device, you should add a suitable
- number of <code>pcie-root-port</code> controllers when defining
- the guest: for example, add
- </p>
-
-<pre>
-<controller type='pci' model='pcie-root'/>
-<controller type='pci' model='pcie-root-port'/>
-<controller type='pci' model='pcie-root-port'/>
-<controller type='pci' model='pcie-root-port'/></pre>
-
- <p>
- if you expect to hotplug up to three PCI Express devices,
- either emulated or assigned from the host. That's all the
- information you need to provide: libvirt will fill in the
- remaining details automatically. Note that you need to add
- the <code>pcie-root</code> controller along with the
- <code>pcie-root-port</code> controllers or you will get an
- error.
- </p>
- <p>
- Note that if you're adding PCI controllers to a guest and at
- the same time you're also adding PCI devices, some of the
- controllers will be used for the newly-added devices and won't
- be available for hotplug once the guest has been started.
- </p>
- <p>
- If you expect to hotplug legacy PCI devices, then you will need
- specialized controllers, since all those mentioned above are
- intended for PCI Express devices only: add
- </p>
-
-<pre>
-<controller type='pci' model='pcie-to-pci-bridge'/></pre>
-
- <p>
- and you'll be able to hotplug up to 31 legacy PCI devices,
- either emulated or assigned from the host, in the slots
- from 0x01 to 0x1f of the <code>pcie-to-pci-bridge</code> controller.
- </p>
-
- <h3><a id="x86_64-i440fx">i440fx (pc) machine type</a></h3>
-
- <p>
- This is a legacy PCI native machine type. The default PCI
- topology looks like
- </p>
-
-<pre>
-<controller type='pci' index='0' model='pci-root'/></pre>
-
- <p>
- where each of the 31 slots (from 0x01 to 0x1f) on the
- <code>pci-root</code> controller is hotplug capable and
- can accept a legacy PCI device, either emulated or
- assigned from the guest.
- </p>
-
- <h2><a id="ppc64">ppc64 architecture</a></h2>
-
- <h3><a id="ppc64-pseries">pseries machine type</a></h3>
-
- <p>
- The default PCI topology for the <code>pseries</code> machine
- type looks like
- </p>
-
-<pre>
-<controller type='pci' index='0' model='pci-root'>
- <model name='spapr-pci-host-bridge'/>
- <target index='0'/>
-</controller></pre>
-
- <p>
- The 31 slots, from 0x01 to 0x1f, on a <code>pci-root</code>
- controller are all hotplug capable and, despite the name
- suggesting otherwise, starting with QEMU 2.9 all of them
- can accept PCI Express devices in addition to legacy PCI
- devices; however, libvirt will only place emulated devices
- on the default <code>pci-root</code> controller.
- </p>
- <p>
- In order to take advantage of improved error reporting and
- recovering capabilities, PCI devices assigned from the
- host need to be isolated by placing each on a separate
- <code>pci-root</code> controller, which has to be prepared
- in advance for hotplug to work: for example, add
- </p>
-
-<pre>
-<controller type='pci' model='pci-root'/>
-<controller type='pci' model='pci-root'/>
-<controller type='pci' model='pci-root'/></pre>
-
- <p>
- if you expect to hotplug up to three PCI devices assigned
- from the host.
- </p>
-
- <h2><a id="aarch64">aarch64 architecture</a></h2>
-
- <h3><a id="aarch64-virt">mach-virt (virt) machine type</a></h3>
-
- <p>
- This machine type mostly behaves the same as the
- <a href="#x86_64-q35">q35 machine type</a>, so you can just
- refer to that section for information.
- </p>
- <p>
- The only difference worth mentioning is that using legacy
- PCI for <code>mach-virt</code> guests is extremely uncommon,
- so you'll probably never need to add controllers other than
- <code>pcie-root-port</code>.
- </p>
-
- </body>
-</html>
diff --git a/docs/pci-hotplug.rst b/docs/pci-hotplug.rst
new file mode 100644
index 0000000000..bc7fdbbd86
--- /dev/null
+++ b/docs/pci-hotplug.rst
@@ -0,0 +1,146 @@
+========================
+PCI topology and hotplug
+========================
+
+.. contents::
+
+Perhaps surprisingly, most libvirt guests support only limited PCI device
+hotplug out of the box, or even none at all.
+
+The reason for this apparent limitation is the fact that each hotplugged PCI
+device might require additional PCI controllers to be added to the guest. Since
+most PCI controllers can't be hotplugged, they need to be added before the guest
+is started; however, libvirt has no way of knowing in advance how many devices
+will be hotplugged during the guest's lifetime, thus making it impossible to
+automatically provide the right amount of PCI controllers: any arbitrary number
+would end up being too big for some users, and too small for others.
+
+Ultimately, the user is the only one who knows how much the guest will need to
+grow dynamically, so the responsibility of planning a suitable PCI topology in
+advance falls on them.
+
+This document aims at providing all the information needed to successfully plan
+the PCI topology of a guest. Note that the details can vary a lot between
+architectures and even machine types, hence the way it's organized.
+
+x86_64 architecture
+-------------------
+
+q35 machine type
+~~~~~~~~~~~~~~~~
+
+This is a PCI Express native machine type. The default PCI topology looks like
+
+::
+
+ <controller type='pci' index='0' model='pcie-root'/>
+ <controller type='pci' index='1' model='pcie-root-port'>
+ <model name='pcie-root-port'/>
+ <target chassis='1' port='0x10'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
+ </controller>
+
+and supports hotplugging a single PCI Express device, either emulated or
+assigned from the host.
+
+If you have a very specific use case, such as the appliances used by
+`libguestfs <https://libguestfs.org/>`__ behind the scenes to access disk
+images, and this automatically-added ``pcie-root-port`` controller ends up being
+a nuisance, you can prevent libvirt from adding it by manually managing PCI
+controllers and addresses according to your needs.
+
+Slots on the ``pcie-root`` controller do not support hotplug, so the device will
+be hotplugged into the ``pcie-root-port`` controller. If you plan to hotplug
+more than a single PCI Express device, you should add a suitable number of
+``pcie-root-port`` controllers when defining the guest: for example, add
+
+::
+
+ <controller type='pci' model='pcie-root'/>
+ <controller type='pci' model='pcie-root-port'/>
+ <controller type='pci' model='pcie-root-port'/>
+ <controller type='pci' model='pcie-root-port'/>
+
+if you expect to hotplug up to three PCI Express devices, either emulated or
+assigned from the host. That's all the information you need to provide: libvirt
+will fill in the remaining details automatically. Note that you need to add the
+``pcie-root`` controller along with the ``pcie-root-port`` controllers or you
+will get an error.
+
+Note that if you're adding PCI controllers to a guest and at the same time
+you're also adding PCI devices, some of the controllers will be used for the
+newly-added devices and won't be available for hotplug once the guest has been
+started.
+
+If you expect to hotplug legacy PCI devices, then you will need specialized
+controllers, since all those mentioned above are intended for PCI Express
+devices only: add
+
+::
+
+ <controller type='pci' model='pcie-to-pci-bridge'/>
+
+and you'll be able to hotplug up to 31 legacy PCI devices, either emulated or
+assigned from the host, in the slots from 0x01 to 0x1f of the
+``pcie-to-pci-bridge`` controller.
+
+i440fx (pc) machine type
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is a legacy PCI native machine type. The default PCI topology looks like
+
+::
+
+ <controller type='pci' index='0' model='pci-root'/>
+
+where each of the 31 slots (from 0x01 to 0x1f) on the ``pci-root`` controller is
+hotplug capable and can accept a legacy PCI device, either emulated or assigned
+from the guest.
+
+ppc64 architecture
+------------------
+
+pseries machine type
+~~~~~~~~~~~~~~~~~~~~
+
+The default PCI topology for the ``pseries`` machine type looks like
+
+::
+
+ <controller type='pci' index='0' model='pci-root'>
+ <model name='spapr-pci-host-bridge'/>
+ <target index='0'/>
+ </controller>
+
+The 31 slots, from 0x01 to 0x1f, on a ``pci-root`` controller are all hotplug
+capable and, despite the name suggesting otherwise, starting with QEMU 2.9 all
+of them can accept PCI Express devices in addition to legacy PCI devices;
+however, libvirt will only place emulated devices on the default ``pci-root``
+controller.
+
+In order to take advantage of improved error reporting and recovering
+capabilities, PCI devices assigned from the host need to be isolated by placing
+each on a separate ``pci-root`` controller, which has to be prepared in advance
+for hotplug to work: for example, add
+
+::
+
+ <controller type='pci' model='pci-root'/>
+ <controller type='pci' model='pci-root'/>
+ <controller type='pci' model='pci-root'/>
+
+if you expect to hotplug up to three PCI devices assigned from the host.
+
+aarch64 architecture
+--------------------
+
+mach-virt (virt) machine type
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This machine type mostly behaves the same as the `q35 machine
+type <#q35-machine-type>`__, so you can just refer to that section for
+information.
+
+The only difference worth mentioning is that using legacy PCI for ``mach-virt``
+guests is extremely uncommon, so you'll probably never need to add controllers
+other than ``pcie-root-port``.
--
2.35.1
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