From af528dcffaab1efea760395cc6676fe4b01e89b5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl> Date: Thu, 9 May 2019 12:34:30 +0200 Subject: [PATCH] man: describe naming schemes in a new man page I decided to make this a separate man page because it is freakin' long. This content could equally well go in systemd-udevd.service(8), systemd.link(5), or a new man page for the net_id builtin. v2: - rename to systemd.net-naming-scheme - add udevadm test-builtin net_id example (cherry picked from commit 0b1e5b6ed8c6b9a2bc53709eb75e381d360f05bf) Related: #1827462 [msekleta: I've removed parts that describe features which are not available in RHEL-8] --- man/rules/meson.build | 1 + man/systemd-udevd.service.xml | 19 +- man/systemd.link.xml | 10 +- man/systemd.net-naming-scheme.xml | 385 ++++++++++++++++++++++++++++++ src/udev/udev-builtin-net_id.c | 1 + 5 files changed, 402 insertions(+), 14 deletions(-) create mode 100644 man/systemd.net-naming-scheme.xml diff --git a/man/rules/meson.build b/man/rules/meson.build index 7ae94ea265..e6c0a99bbd 100644 --- a/man/rules/meson.build +++ b/man/rules/meson.build @@ -714,6 +714,7 @@ manpages = [ ['systemd.kill', '5', [], ''], ['systemd.link', '5', [], ''], ['systemd.mount', '5', [], ''], + ['systemd.net-naming-scheme', '7', [], ''], ['systemd.netdev', '5', [], 'ENABLE_NETWORKD'], ['systemd.network', '5', [], 'ENABLE_NETWORKD'], ['systemd.nspawn', '5', [], ''], diff --git a/man/systemd-udevd.service.xml b/man/systemd-udevd.service.xml index b738591c93..f4cdb2f1e7 100644 --- a/man/systemd-udevd.service.xml +++ b/man/systemd-udevd.service.xml @@ -174,15 +174,11 @@ <term><varname>net.naming-scheme=</varname></term> <listitem> <para>Network interfaces are renamed to give them predictable names when possible (unless - <varname>net.ifnames=0</varname> is specified, see above). The names are derived from various - device metadata fields. Newer versions of <filename>systemd-udevd.service</filename> take more of - these fields into account, improving (and thus possibly changing) the names used for the same - devices. With this kernel command line option it is possible to pick a specific version of this - algorithm. It expects a naming scheme identifier as argument. Currently the following identifiers - are known: <literal>rhel-8.0</literal>, <literal>rhel-8.1</literal>, <literal>rhel-8.2</literal>, - <literal>rhel-8.3</literal> which each implement the naming scheme that was the default in the - indicated Red Hat Enterprise Linux minor version. In addition, <literal>latest</literal> may be - used to designate the latest scheme known (to this particular version of + <varname>net.ifnames=0</varname> is specified, see above). With this kernel command line option it + is possible to pick a specific version of this algorithm and override the default chosen at + compilation time. Expects one of the naming scheme identifiers listed in + <citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + or <literal>latest</literal> to select the latest scheme known (to this particular version of <filename>systemd-udevd.service</filename>).</para> <para>Note that selecting a specific scheme is not sufficient to fully stabilize interface naming: the naming is generally derived from driver attributes exposed by the kernel. As the kernel is @@ -191,9 +187,8 @@ </listitem> </varlistentry> </variablelist> - <!-- when adding entries here, consider also adding them - in kernel-command-line.xml --> - </refsect1> + <!-- when adding entries here, consider also adding them in kernel-command-line.xml --> + </refsect1> <refsect1> <title>See Also</title> diff --git a/man/systemd.link.xml b/man/systemd.link.xml index 6708753e82..32657308d0 100644 --- a/man/systemd.link.xml +++ b/man/systemd.link.xml @@ -286,6 +286,7 @@ <para>The name is set based on information given by the firmware for on-board devices, as exported by the udev property <literal>ID_NET_NAME_ONBOARD</literal>. + See <citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>. </para> </listitem> </varlistentry> @@ -295,6 +296,7 @@ <para>The name is set based on information given by the firmware for hot-plug devices, as exported by the udev property <literal>ID_NET_NAME_SLOT</literal>. + See <citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>. </para> </listitem> </varlistentry> @@ -303,7 +305,9 @@ <listitem> <para>The name is set based on the device's physical location, as exported by the udev property - <literal>ID_NET_NAME_PATH</literal>.</para> + <literal>ID_NET_NAME_PATH</literal>. + See <citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>. + </para> </listitem> </varlistentry> <varlistentry> @@ -311,7 +315,9 @@ <listitem> <para>The name is set based on the device's persistent MAC address, as exported by the udev property - <literal>ID_NET_NAME_MAC</literal>.</para> + <literal>ID_NET_NAME_MAC</literal>. + See <citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>. + </para> </listitem> </varlistentry> </variablelist> diff --git a/man/systemd.net-naming-scheme.xml b/man/systemd.net-naming-scheme.xml new file mode 100644 index 0000000000..a12cc3c460 --- /dev/null +++ b/man/systemd.net-naming-scheme.xml @@ -0,0 +1,385 @@ +<?xml version='1.0'?> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1+ --> + +<refentry id="systemd.net-naming-scheme"> + <refentryinfo> + <title>systemd.net-naming-scheme</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>systemd.net-naming-scheme</refentrytitle> + <manvolnum>7</manvolnum> + </refmeta> + + <refnamediv> + <refname>systemd.net-naming-scheme</refname> + <refpurpose>Network device naming schemes</refpurpose> + </refnamediv> + + <refsect1> + <title>Description</title> + + <para>Network interfaces may be renamed to give them predictable names when there's enough information to + generate appropriate names and the use of certain types of names is configured. This page describes the + first part, i.e. what possible names may be generated. Those names are generated by the + <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> + builtin <command>net_id</command> and exported as udev properties + (<varname>ID_NET_NAME_ONBOARD=</varname>, <varname>ID_NET_LABEL_ONBOARD=</varname>, + <varname>ID_NET_NAME_PATH=</varname>, <varname>ID_NET_NAME_SLOT=</varname>).</para> + + <para>Names are derived from various device metadata attributes. Newer versions of udev take more of + these attributes into account, improving (and thus possibly changing) the names used for the same + devices. Differents version of the naming rules are called "naming schemes". The default naming scheme is + chosen at compilation time. Usually this will be the latest implemented version, but it is also possible + to set one of the older versions to preserve compatibility. This may be useful for example for + distributions, which may introduce new versions of systemd in stable releases without changing the naming + scheme. The naming scheme may also be overriden using the <varname>net.naming-scheme=</varname> kernel + command line switch, see + <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. + Available naming schemes are described below.</para> + + <para>After the udev proprties have been generated, appropriate udev rules may be used to actually rename + devices based on those properties. See the description of <varname>NamePolicy=</varname> in + <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>. + </para> + </refsect1> + + <refsect1> + <title>Naming</title> + + <para>All names start with a two-character prefix that signifies the interface type.</para> + + <table> + <title>Two character prefixes based on the type of interface</title> + + <tgroup cols='2'> + <thead> + <row> + <entry>Prefix</entry> + <entry>Description</entry> + </row> + </thead> + <tbody> + <row> + <entry><constant>en</constant></entry> + <entry>Ethernet</entry> + </row> + <row> + <entry><constant>sl</constant></entry> + <entry>serial line IP (slip)</entry> + </row> + <row> + <entry><constant>wl</constant></entry> + <entry>Wireless local area network (WLAN)</entry> + </row> + <row> + <entry><constant>ww</constant></entry> + <entry>Wireless wide area network (WWAN)</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>The udev <command>net_id</command> builtin exports the following udev device properties:</para> + + <variablelist> + <varlistentry> + <term><varname>ID_NET_NAME_ONBOARD=<replaceable>prefix</replaceable><constant>o</constant><replaceable>number</replaceable></varname></term> + + <listitem><para>This name is set based on the ordering information given by the firmware for + on-board devices. The name consists of the prefix, letter <constant>o</constant>, and a number + specified by the firmware. This is only available for PCI devices.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ID_NET_LABEL_ONBOARD=<replaceable>prefix</replaceable> <replaceable>label</replaceable></varname></term> + + <listitem><para>This property is set based on label given by the firmware for on-board devices. The + name consists of the prefix concatenated with the label. This is only available for PCI devices. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ID_NET_NAME_MAC=<replaceable>prefix</replaceable><constant>x</constant><replaceable>AABBCCDDEEFF</replaceable></varname></term> + + <listitem><para>This name consists of the prefix, letter <constant>x</constant>, and 12 hexadecimal + digits of the MAC address. It is available if the device has a fixed MAC address. Because this name + is based on an attribute of the card itself, it remains "stable" when the device is moved (even + between machines), but will change when the hardware is replaced.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]</varname></term> + <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>b</constant><replaceable>number</replaceable></varname></term> + <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>u</constant><replaceable>port</replaceable>…[<constant>c</constant><replaceable>config</replaceable>][<constant>i</constant><replaceable>interface</replaceable>]</varname></term> + <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>v</constant><replaceable>slot</replaceable></varname></term> + + <listitem><para>This property describes the slot position. Different schemes are used depending on + the bus type, as described in the table below. In all cases, PCI slot information must be known. In + case of USB, BCMA, and SR-VIO devices, the full name consists of the prefix, PCI slot identifier, + and USB or BCMA or SR-VIO slot identifier. The first two parts are denoted as "…" in the table + below.</para> + + <table> + <title>Slot naming schemes</title> + + <tgroup cols='2'> + <thead> + <row> + <entry>Format</entry> + <entry>Description</entry> + </row> + </thead> + + <tbody> + <row> + <entry><replaceable>prefix</replaceable> [<constant>P</constant><replaceable>domain</replaceable>] <constant>s</constant><replaceable>slot</replaceable> [<constant>f</constant><replaceable>function</replaceable>] [<constant>n</constant><replaceable>port_name</replaceable> | <constant>d</constant><replaceable>dev_port</replaceable>]</entry> + <entry>PCI slot number</entry> + </row> + + <row> + <entry>… <constant>b</constant><replaceable>number</replaceable></entry> + <entry>Broadcom bus (BCMA) core number</entry> + </row> + + <row> + <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry> + <entry>USB port number chain</entry> + </row> + + <row> + <entry>… <constant>v</constant><replaceable>slot</replaceable></entry> + <entry>SR-VIO slot number</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>The PCI domain is only prepended when it is not 0. All multi-function PCI devices will carry + the <constant>f<replaceable>function</replaceable></constant> number in the device name, including + the function 0 device. For non-multi-function devices, the number is suppressed if 0. The port name + <replaceable>port_name</replaceable> is used, or the port number + <constant>d</constant><replaceable>dev_port</replaceable> if the name is not known.</para> + + <para>For BCMA devices, the core number is suppressed when 0.</para> + + <para>For USB devices the full chain of port numbers of hubs is composed. If the name gets longer + than the maximum number of 15 characters, the name is not exported. The usual USB configuration + number 1 and interface number 0 values are suppressed.</para> + </listitem> + + <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of + <constant>v</constant> and the virtual device number, with any leading zeros removed. The bus + number is ignored. This device type is found in IBM PowerVMs.</para> + </varlistentry> + + <varlistentry> + <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>c</constant><replaceable>bus_id</replaceable></varname></term> + <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>a</constant><replaceable>vendor</replaceable><replaceable>model</replaceable><constant>i</constant><replaceable>instance</replaceable></varname></term> + <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>i</constant><replaceable>address</replaceable><constant>n</constant><replaceable>port_name</replaceable></varname></term> + <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]</varname></term> + <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>b</constant><replaceable>number</replaceable></varname></term> + <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>u</constant><replaceable>port</replaceable>…[<constant>c</constant><replaceable>config</replaceable>][<constant>i</constant><replaceable>interface</replaceable>]</varname></term> + + <listitem><para>This property describes the device installation location. Different schemes are + used depending on the bus type, as described in the table below. For BCMA and USB devices, PCI path + information must known, and the full name consists of the prefix, PCI slot identifier, and USB or + BCMA location. The first two parts are denoted as "…" in the table below.</para> + + <table> + <title>Path naming schemes</title> + + <tgroup cols='2'> + <thead> + <row> + <entry>Format</entry> + <entry>Description</entry> + </row> + </thead> + + <tbody> + <row> + <entry><replaceable>prefix</replaceable> <constant>c</constant><replaceable>bus_id</replaceable></entry> + <entry>CCW or grouped CCW device identifier</entry> + </row> + + <row> + <entry><replaceable>prefix</replaceable> <constant>a</constant><replaceable>vendor</replaceable> <replaceable>model</replaceable> <constant>i</constant><replaceable>instance</replaceable></entry> + <entry>ACPI path names for ARM64 platform devices</entry> + </row> + + <row> + <entry><replaceable>prefix</replaceable> [<constant>P</constant><replaceable>domain</replaceable>] <constant>p</constant><replaceable>bus</replaceable> <constant>s</constant><replaceable>slot</replaceable> [<constant>f</constant><replaceable>function</replaceable>] [<constant>n</constant><replaceable>phys_port_name</replaceable> | <constant>d</constant><replaceable>dev_port</replaceable>]</entry> + <entry>PCI geographical location</entry> + </row> + + <row> + <entry>… <constant>b</constant><replaceable>number</replaceable></entry> + <entry>Broadcom bus (BCMA) core number</entry> + </row> + + <row> + <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry> + <entry>USB port number chain</entry> + </row> + + </tbody> + </tgroup> + </table> + + <para>CCW and grouped CCW devices are found in IBM System Z mainframes. Any leading zeros and + dots are suppressed.</para> + + <para>For PCI, BCMA, and USB devices, the same rules as described above for slot naming are + used.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>History</title> + + <para>The following "naming schemes" have been defined:</para> + + <variablelist> + <varlistentry> + <term><constant>rhel-8.0</constant></term> + + <listitem><para>Naming was changed for virtual network interfaces created with SR-IOV and NPAR and + for devices where the PCI network controller device does not have a slot number associated.</para> + + <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of + <literal>v<replaceable>port</replaceable></literal>, where <replaceable>port</replaceable> is the + virtual device number. Previously those virtual devices were named as if completely independent. + </para> + + <para>The ninth and later NPAR virtual devices are named following the scheme used for the first + eight NPAR partitions. Previously those devices were not renamed and the kernel default + ("eth<replaceable>N</replaceable>") was used.</para> + + <para>Names are also generated for PCI devices where the PCI network controller device does not + have an associated slot number itself, but one of its parents does. Previously those devices were + not renamed and the kernel default was used.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>rhel-8.1</constant></term> + + <para>Same as naming scheme <constant>rhel-8.0</constant>.</para> + </varlistentry> + + <varlistentry> + <term><constant>rhel-8.2</constant></term> + + <para>Same as naming scheme <constant>rhel-8.0</constant>.</para> + </varlistentry> + + <varlistentry> + <term><constant>rhel-8.3</constant></term> + + <para>Same as naming scheme <constant>rhel-8.0</constant>.</para> + </varlistentry> + + <para>Note that <constant>latest</constant> may be used to denote the latest scheme known (to this + particular version of systemd.</para> + </variablelist> + </refsect1> + + <refsect1> + <title>Examples</title> + + <example> + <title>Using <command>udevadm test-builtin</command> to display device properties</title> + + <programlisting>$ udevadm test-builtin net_id /sys/class/net/enp0s31f6 +... +Using default interface naming scheme 'rhel-8.3'. +ID_NET_NAMING_SCHEME=rhel-8.3 +ID_NET_NAME_MAC=enx54ee75cb1dc0 +ID_OUI_FROM_DATABASE=Wistron InfoComm(Kunshan)Co.,Ltd. +ID_NET_NAME_PATH=enp0s31f6 +...</programlisting> + </example> + + <example> + <title>PCI Ethernet card with firmware index "1"</title> + + <programlisting>ID_NET_NAME_ONBOARD=eno1 +ID_NET_NAME_ONBOARD_LABEL=enEthernet Port 1 + </programlisting> + <!-- FIXME: nuke the prefix! --> + </example> + + <example> + <title>PCI Ethernet card in hotplug slot with firmware index number</title> + + <programlisting># /sys/devices/pci0000:00/0000:00:1c.3/0000:05:00.0/net/ens1 +ID_NET_NAME_MAC=enx000000000466 +ID_NET_NAME_PATH=enp5s0 +ID_NET_NAME_SLOT=ens1</programlisting> + </example> + + <example> + <title>PCI Ethernet multi-function card with 2 ports</title> + + <programlisting># /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/enp2s0f0 +ID_NET_NAME_MAC=enx78e7d1ea46da +ID_NET_NAME_PATH=enp2s0f0 + +# /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.1/net/enp2s0f1 +ID_NET_NAME_MAC=enx78e7d1ea46dc +ID_NET_NAME_PATH=enp2s0f1</programlisting> + </example> + + <example> + <title>PCI WLAN card</title> + + <programlisting># /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/wlp3s0 +ID_NET_NAME_MAC=wlx0024d7e31130 +ID_NET_NAME_PATH=wlp3s0</programlisting> + </example> + + <example> + <title>USB built-in 3G modem</title> + + <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.4/2-1.4:1.6/net/wwp0s29u1u4i6 +ID_NET_NAME_MAC=wwx028037ec0200 +ID_NET_NAME_PATH=wwp0s29u1u4i6</programlisting> + </example> + + <example> + <title>USB Android phone</title> + + <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/net/enp0s29u1u2 +ID_NET_NAME_MAC=enxd626b3450fb5 +ID_NET_NAME_PATH=enp0s29u1u2</programlisting> + </example> + + <example> + <title>s390 grouped CCW interface</title> + + <programlisting># /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0 +ID_NET_NAME_MAC=enx026d3c00000a +ID_NET_NAME_PATH=encf5f0</programlisting> + </example> + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <ulink url="https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames">the + original page describing stable interface names</ulink> + </para> + </refsect1> + +</refentry> diff --git a/src/udev/udev-builtin-net_id.c b/src/udev/udev-builtin-net_id.c index d85dc2848b..aa553d5ade 100644 --- a/src/udev/udev-builtin-net_id.c +++ b/src/udev/udev-builtin-net_id.c @@ -78,6 +78,7 @@ * /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0 * ID_NET_NAME_MAC=enx026d3c00000a * ID_NET_NAME_PATH=encf5f0 + * When the code here is changed, man/systemd.net-naming-scheme.xml must be updated too. */ #include <errno.h>