Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 521 insertions, 0 deletions

diff --git a/Documentation/doc-guide/sphinx.rst b/Documentation/doc-guide/sphinx.rst
new file mode 100644
index 000000000..23edb427e
--- /dev/null
+++ b/Documentation/doc-guide/sphinx.rst
@@ -0,0 +1,521 @@
+.. _sphinxdoc:
+
+=====================================
+Using Sphinx for kernel documentation
+=====================================
+
+The Linux kernel uses `Sphinx`_ to generate pretty documentation from
+`reStructuredText`_ files under ``Documentation``. To build the documentation in
+HTML or PDF formats, use ``make htmldocs`` or ``make pdfdocs``. The generated
+documentation is placed in ``Documentation/output``.
+
+.. _Sphinx: http://www.sphinx-doc.org/
+.. _reStructuredText: http://docutils.sourceforge.net/rst.html
+
+The reStructuredText files may contain directives to include structured
+documentation comments, or kernel-doc comments, from source files. Usually these
+are used to describe the functions and types and design of the code. The
+kernel-doc comments have some special structure and formatting, but beyond that
+they are also treated as reStructuredText.
+
+Finally, there are thousands of plain text documentation files scattered around
+``Documentation``. Some of these will likely be converted to reStructuredText
+over time, but the bulk of them will remain in plain text.
+
+.. _sphinx_install:
+
+Sphinx Install
+==============
+
+The ReST markups currently used by the Documentation/ files are meant to be
+built with ``Sphinx`` version 1.7 or higher.
+
+There's a script that checks for the Sphinx requirements. Please see
+:ref:`sphinx-pre-install` for further details.
+
+Most distributions are shipped with Sphinx, but its toolchain is fragile,
+and it is not uncommon that upgrading it or some other Python packages
+on your machine would cause the documentation build to break.
+
+A way to avoid that is to use a different version than the one shipped
+with your distributions. In order to do so, it is recommended to install
+Sphinx inside a virtual environment, using ``virtualenv-3``
+or ``virtualenv``, depending on how your distribution packaged Python 3.
+
+.. note::
+
+   #) It is recommended to use the RTD theme for html output. Depending
+      on the Sphinx version, it should be installed separately,
+      with ``pip install sphinx_rtd_theme``.
+
+In summary, if you want to install Sphinx version 2.4.4, you should do::
+
+       $ virtualenv sphinx_2.4.4
+       $ . sphinx_2.4.4/bin/activate
+       (sphinx_2.4.4) $ pip install -r Documentation/sphinx/requirements.txt
+
+After running ``. sphinx_2.4.4/bin/activate``, the prompt will change,
+in order to indicate that you're using the new environment. If you
+open a new shell, you need to rerun this command to enter again at
+the virtual environment before building the documentation.
+
+Image output
+------------
+
+The kernel documentation build system contains an extension that
+handles images on both GraphViz and SVG formats (see
+:ref:`sphinx_kfigure`).
+
+For it to work, you need to install both GraphViz and ImageMagick
+packages. If those packages are not installed, the build system will
+still build the documentation, but won't include any images at the
+output.
+
+PDF and LaTeX builds
+--------------------
+
+Such builds are currently supported only with Sphinx versions 2.4 and higher.
+
+For PDF and LaTeX output, you'll also need ``XeLaTeX`` version 3.14159265.
+
+Depending on the distribution, you may also need to install a series of
+``texlive`` packages that provide the minimal set of functionalities
+required for ``XeLaTeX`` to work.
+
+Math Expressions in HTML
+------------------------
+
+Some ReST pages contain math expressions. Due to the way Sphinx works,
+those expressions are written using LaTeX notation.
+There are two options for Sphinx to render math expressions in html output.
+One is an extension called `imgmath`_ which converts math expressions into
+images and embeds them in html pages.
+The other is an extension called `mathjax`_ which delegates math rendering
+to JavaScript capable web browsers.
+The former was the only option for pre-6.1 kernel documentation and it
+requires quite a few texlive packages including amsfonts and amsmath among
+others.
+
+Since kernel release 6.1, html pages with math expressions can be built
+without installing any texlive packages. See `Choice of Math Renderer`_ for
+further info.
+
+.. _imgmath: https://www.sphinx-doc.org/en/master/usage/extensions/math.html#module-sphinx.ext.imgmath
+.. _mathjax: https://www.sphinx-doc.org/en/master/usage/extensions/math.html#module-sphinx.ext.mathjax
+
+.. _sphinx-pre-install:
+
+Checking for Sphinx dependencies
+--------------------------------
+
+There's a script that automatically check for Sphinx dependencies. If it can
+recognize your distribution, it will also give a hint about the install
+command line options for your distro::
+
+	$ ./scripts/sphinx-pre-install
+	Checking if the needed tools for Fedora release 26 (Twenty Six) are available
+	Warning: better to also install "texlive-luatex85".
+	You should run:
+
+		sudo dnf install -y texlive-luatex85
+		/usr/bin/virtualenv sphinx_2.4.4
+		. sphinx_2.4.4/bin/activate
+		pip install -r Documentation/sphinx/requirements.txt
+
+	Can't build as 1 mandatory dependency is missing at ./scripts/sphinx-pre-install line 468.
+
+By default, it checks all the requirements for both html and PDF, including
+the requirements for images, math expressions and LaTeX build, and assumes
+that a virtual Python environment will be used. The ones needed for html
+builds are assumed to be mandatory; the others to be optional.
+
+It supports two optional parameters:
+
+``--no-pdf``
+	Disable checks for PDF;
+
+``--no-virtualenv``
+	Use OS packaging for Sphinx instead of Python virtual environment.
+
+
+Sphinx Build
+============
+
+The usual way to generate the documentation is to run ``make htmldocs`` or
+``make pdfdocs``. There are also other formats available: see the documentation
+section of ``make help``. The generated documentation is placed in
+format-specific subdirectories under ``Documentation/output``.
+
+To generate documentation, Sphinx (``sphinx-build``) must obviously be
+installed.  For PDF output you'll also need ``XeLaTeX`` and ``convert(1)``
+from ImageMagick (https://www.imagemagick.org).\ [#ink]_ All of these are
+widely available and packaged in distributions.
+
+To pass extra options to Sphinx, you can use the ``SPHINXOPTS`` make
+variable. For example, use ``make SPHINXOPTS=-v htmldocs`` to get more verbose
+output.
+
+It is also possible to pass an extra DOCS_CSS overlay file, in order to customize
+the html layout, by using the ``DOCS_CSS`` make variable.
+
+By default, the "Alabaster" theme is used to build the HTML documentation;
+this theme is bundled with Sphinx and need not be installed separately.
+The Sphinx theme can be overridden by using the ``DOCS_THEME`` make variable.
+
+There is another make variable ``SPHINXDIRS``, which is useful when test
+building a subset of documentation.  For example, you can build documents
+under ``Documentation/doc-guide`` by running
+``make SPHINXDIRS=doc-guide htmldocs``.
+The documentation section of ``make help`` will show you the list of
+subdirectories you can specify.
+
+To remove the generated documentation, run ``make cleandocs``.
+
+.. [#ink] Having ``inkscape(1)`` from Inkscape (https://inkscape.org)
+	  as well would improve the quality of images embedded in PDF
+	  documents, especially for kernel releases 5.18 and later.
+
+Choice of Math Renderer
+-----------------------
+
+Since kernel release 6.1, mathjax works as a fallback math renderer for
+html output.\ [#sph1_8]_
+
+Math renderer is chosen depending on available commands as shown below:
+
+.. table:: Math Renderer Choices for HTML
+
+    ============= ================= ============
+    Math renderer Required commands Image format
+    ============= ================= ============
+    imgmath       latex, dvipng     PNG (raster)
+    mathjax
+    ============= ================= ============
+
+The choice can be overridden by setting an environment variable
+``SPHINX_IMGMATH`` as shown below:
+
+.. table:: Effect of Setting ``SPHINX_IMGMATH``
+
+    ====================== ========
+    Setting                Renderer
+    ====================== ========
+    ``SPHINX_IMGMATH=yes`` imgmath
+    ``SPHINX_IMGMATH=no``  mathjax
+    ====================== ========
+
+.. [#sph1_8] Fallback of math renderer requires Sphinx >=1.8.
+
+
+Writing Documentation
+=====================
+
+Adding new documentation can be as simple as:
+
+1. Add a new ``.rst`` file somewhere under ``Documentation``.
+2. Refer to it from the Sphinx main `TOC tree`_ in ``Documentation/index.rst``.
+
+.. _TOC tree: http://www.sphinx-doc.org/en/stable/markup/toctree.html
+
+This is usually good enough for simple documentation (like the one you're
+reading right now), but for larger documents it may be advisable to create a
+subdirectory (or use an existing one). For example, the graphics subsystem
+documentation is under ``Documentation/gpu``, split to several ``.rst`` files,
+and has a separate ``index.rst`` (with a ``toctree`` of its own) referenced from
+the main index.
+
+See the documentation for `Sphinx`_ and `reStructuredText`_ on what you can do
+with them. In particular, the Sphinx `reStructuredText Primer`_ is a good place
+to get started with reStructuredText. There are also some `Sphinx specific
+markup constructs`_.
+
+.. _reStructuredText Primer: http://www.sphinx-doc.org/en/stable/rest.html
+.. _Sphinx specific markup constructs: http://www.sphinx-doc.org/en/stable/markup/index.html
+
+Specific guidelines for the kernel documentation
+------------------------------------------------
+
+Here are some specific guidelines for the kernel documentation:
+
+* Please don't go overboard with reStructuredText markup. Keep it
+  simple. For the most part the documentation should be plain text with
+  just enough consistency in formatting that it can be converted to
+  other formats.
+
+* Please keep the formatting changes minimal when converting existing
+  documentation to reStructuredText.
+
+* Also update the content, not just the formatting, when converting
+  documentation.
+
+* Please stick to this order of heading adornments:
+
+  1. ``=`` with overline for document title::
+
+       ==============
+       Document title
+       ==============
+
+  2. ``=`` for chapters::
+
+       Chapters
+       ========
+
+  3. ``-`` for sections::
+
+       Section
+       -------
+
+  4. ``~`` for subsections::
+
+       Subsection
+       ~~~~~~~~~~
+
+  Although RST doesn't mandate a specific order ("Rather than imposing a fixed
+  number and order of section title adornment styles, the order enforced will be
+  the order as encountered."), having the higher levels the same overall makes
+  it easier to follow the documents.
+
+* For inserting fixed width text blocks (for code examples, use case
+  examples, etc.), use ``::`` for anything that doesn't really benefit
+  from syntax highlighting, especially short snippets. Use
+  ``.. code-block:: <language>`` for longer code blocks that benefit
+  from highlighting. For a short snippet of code embedded in the text, use \`\`.
+
+
+the C domain
+------------
+
+The **Sphinx C Domain** (name c) is suited for documentation of C API. E.g. a
+function prototype:
+
+.. code-block:: rst
+
+    .. c:function:: int ioctl( int fd, int request )
+
+The C domain of the kernel-doc has some additional features. E.g. you can
+*rename* the reference name of a function with a common name like ``open`` or
+``ioctl``:
+
+.. code-block:: rst
+
+     .. c:function:: int ioctl( int fd, int request )
+        :name: VIDIOC_LOG_STATUS
+
+The func-name (e.g. ioctl) remains in the output but the ref-name changed from
+``ioctl`` to ``VIDIOC_LOG_STATUS``. The index entry for this function is also
+changed to ``VIDIOC_LOG_STATUS``.
+
+Please note that there is no need to use ``c:func:`` to generate cross
+references to function documentation.  Due to some Sphinx extension magic,
+the documentation build system will automatically turn a reference to
+``function()`` into a cross reference if an index entry for the given
+function name exists.  If you see ``c:func:`` use in a kernel document,
+please feel free to remove it.
+
+
+list tables
+-----------
+
+The list-table formats can be useful for tables that are not easily laid
+out in the usual Sphinx ASCII-art formats.  These formats are nearly
+impossible for readers of the plain-text documents to understand, though,
+and should be avoided in the absence of a strong justification for their
+use.
+
+The ``flat-table`` is a double-stage list similar to the ``list-table`` with
+some additional features:
+
+* column-span: with the role ``cspan`` a cell can be extended through
+  additional columns
+
+* row-span: with the role ``rspan`` a cell can be extended through
+  additional rows
+
+* auto span rightmost cell of a table row over the missing cells on the right
+  side of that table-row.  With Option ``:fill-cells:`` this behavior can
+  changed from *auto span* to *auto fill*, which automatically inserts (empty)
+  cells instead of spanning the last cell.
+
+options:
+
+* ``:header-rows:``   [int] count of header rows
+* ``:stub-columns:``  [int] count of stub columns
+* ``:widths:``        [[int] [int] ... ] widths of columns
+* ``:fill-cells:``    instead of auto-spanning missing cells, insert missing cells
+
+roles:
+
+* ``:cspan:`` [int] additional columns (*morecols*)
+* ``:rspan:`` [int] additional rows (*morerows*)
+
+The example below shows how to use this markup.  The first level of the staged
+list is the *table-row*. In the *table-row* there is only one markup allowed,
+the list of the cells in this *table-row*. Exceptions are *comments* ( ``..`` )
+and *targets* (e.g. a ref to ``:ref:`last row <last row>``` / :ref:`last row
+<last row>`).
+
+.. code-block:: rst
+
+   .. flat-table:: table title
+      :widths: 2 1 1 3
+
+      * - head col 1
+        - head col 2
+        - head col 3
+        - head col 4
+
+      * - row 1
+        - field 1.1
+        - field 1.2 with autospan
+
+      * - row 2
+        - field 2.1
+        - :rspan:`1` :cspan:`1` field 2.2 - 3.3
+
+      * .. _`last row`:
+
+        - row 3
+
+Rendered as:
+
+   .. flat-table:: table title
+      :widths: 2 1 1 3
+
+      * - head col 1
+        - head col 2
+        - head col 3
+        - head col 4
+
+      * - row 1
+        - field 1.1
+        - field 1.2 with autospan
+
+      * - row 2
+        - field 2.1
+        - :rspan:`1` :cspan:`1` field 2.2 - 3.3
+
+      * .. _`last row`:
+
+        - row 3
+
+Cross-referencing
+-----------------
+
+Cross-referencing from one documentation page to another can be done simply by
+writing the path to the document file, no special syntax required. The path can
+be either absolute or relative. For absolute paths, start it with
+"Documentation/". For example, to cross-reference to this page, all the
+following are valid options, depending on the current document's directory (note
+that the ``.rst`` extension is required)::
+
+    See Documentation/doc-guide/sphinx.rst. This always works.
+    Take a look at sphinx.rst, which is at this same directory.
+    Read ../sphinx.rst, which is one directory above.
+
+If you want the link to have a different rendered text other than the document's
+title, you need to use Sphinx's ``doc`` role. For example::
+
+    See :doc:`my custom link text for document sphinx <sphinx>`.
+
+For most use cases, the former is preferred, as it is cleaner and more suited
+for people reading the source files. If you come across a ``:doc:`` usage that
+isn't adding any value, please feel free to convert it to just the document
+path.
+
+For information on cross-referencing to kernel-doc functions or types, see
+Documentation/doc-guide/kernel-doc.rst.
+
+.. _sphinx_kfigure:
+
+Figures & Images
+================
+
+If you want to add an image, you should use the ``kernel-figure`` and
+``kernel-image`` directives. E.g. to insert a figure with a scalable
+image format, use SVG (:ref:`svg_image_example`)::
+
+    .. kernel-figure::  svg_image.svg
+       :alt:    simple SVG image
+
+       SVG image example
+
+.. _svg_image_example:
+
+.. kernel-figure::  svg_image.svg
+   :alt:    simple SVG image
+
+   SVG image example
+
+The kernel figure (and image) directive supports **DOT** formatted files, see
+
+* DOT: http://graphviz.org/pdf/dotguide.pdf
+* Graphviz: http://www.graphviz.org/content/dot-language
+
+A simple example (:ref:`hello_dot_file`)::
+
+  .. kernel-figure::  hello.dot
+     :alt:    hello world
+
+     DOT's hello world example
+
+.. _hello_dot_file:
+
+.. kernel-figure::  hello.dot
+   :alt:    hello world
+
+   DOT's hello world example
+
+Embedded *render* markups (or languages) like Graphviz's **DOT** are provided by the
+``kernel-render`` directives.::
+
+  .. kernel-render:: DOT
+     :alt: foobar digraph
+     :caption: Embedded **DOT** (Graphviz) code
+
+     digraph foo {
+      "bar" -> "baz";
+     }
+
+How this will be rendered depends on the installed tools. If Graphviz is
+installed, you will see a vector image. If not, the raw markup is inserted as
+*literal-block* (:ref:`hello_dot_render`).
+
+.. _hello_dot_render:
+
+.. kernel-render:: DOT
+   :alt: foobar digraph
+   :caption: Embedded **DOT** (Graphviz) code
+
+   digraph foo {
+      "bar" -> "baz";
+   }
+
+The *render* directive has all the options known from the *figure* directive,
+plus option ``caption``.  If ``caption`` has a value, a *figure* node is
+inserted. If not, an *image* node is inserted. A ``caption`` is also needed, if
+you want to refer to it (:ref:`hello_svg_render`).
+
+Embedded **SVG**::
+
+  .. kernel-render:: SVG
+     :caption: Embedded **SVG** markup
+     :alt: so-nw-arrow
+
+     <?xml version="1.0" encoding="UTF-8"?>
+     <svg xmlns="http://www.w3.org/2000/svg" version="1.1" ...>
+        ...
+     </svg>
+
+.. _hello_svg_render:
+
+.. kernel-render:: SVG
+   :caption: Embedded **SVG** markup
+   :alt: so-nw-arrow
+
+   <?xml version="1.0" encoding="UTF-8"?>
+   <svg xmlns="http://www.w3.org/2000/svg"
+     version="1.1" baseProfile="full" width="70px" height="40px" viewBox="0 0 700 400">
+   <line x1="180" y1="370" x2="500" y2="50" stroke="black" stroke-width="15px"/>
+   <polygon points="585 0 525 25 585 50" transform="rotate(135 525 25)"/>
+   </svg>