source: postlfs/config/firmware.xml@ c2ee90d4

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<sect1 id="postlfs-firmware" xreflabel="About Firmware">
  <?dbhtml filename="firmware.html"?>

  <sect1info>
    <date>$Date$</date>
  </sect1info>

  <title>About Firmware</title>

  <indexterm zone="postlfs-firmware">
    <primary sortas="e-lib-firmware">/lib/firmware</primary>
  </indexterm>

  <para>
    On some recent PCs it can be necessary, or desirable, to load firmware
    to make them work at their best. There is a directory, <filename
    class="directory">/lib/firmware</filename>, where the kernel or kernel
    drivers look for firmware images.
  </para>

  <para>
    Currently, most firmware can be found at a <userinput>git</userinput>
    repository: <ulink url=
      "http://git.kernel.org/cgit/linux/kernel/git/firmware/linux-firmware.git/tree/"/>.
    For convenience, the LFS Project has created a mirror, updated daily, where
    these firmware files can be accessed via <userinput>wget</userinput> or a
    web browser at <ulink url="&sources-anduin-http;/linux-firmware/"/>.
  </para>

  <para>
    To get the firmware, either point a browser to one of the above
    repositories and then download the item(s) which you need, or install
    <xref linkend="git"/> and clone that repository.
  </para>

  <para>
    For some other firmware, particularly for Intel microcode and certain
    wifi devices, the needed firmware is not available in the above repository.
    Some of this will be addressed below, but a search of the Internet for
    needed firmware is sometimes necessary.
  </para>

  <para>
    Firmware files are conventionally referred to as blobs because you cannot
    determine what they will do. Note that firmware is distributed under
    various different licenses which do not permit disassembly or
    reverse-engineering.
  </para>

  <para>
    Firmware for PCs falls into four categories:
  </para>

  <itemizedlist spacing="compact">
    <listitem>
      <para>
        Updates to the CPU to work around errata, usually referred to as
        microcode.
      </para>
    </listitem>
    <listitem>
      <para>
        Firmware for video controllers. On x86 machines this is required for
        ATI devices (Radeon and AMDGPU chips) and may be useful for Intel (Skylake
        and later) and Nvidia (Kepler and later) GPUs.
      </para>

      <para>
        ATI Radeon and AMGPU devices all require firmware to be able to use KMS
        (kernel modesetting - the preferred option) as well as for Xorg. For
        old radeon chips (before the R600), the firmware is still in the
        kernel source.
      </para>

      <para>
        Intel integrated GPUs from Skylake onwards can use firmware for GuC
        (the Graphics microcontroller), and also for the HuC (HEVC/H265
        microcontroller which offloads to the GPU) and the DMC (Display
        Microcontroller) to provide additional low-power states. The GuC and
        HuC have had a chequered history in the kernel and updated firmware
        may be disabled by default, depending on your kernel version. Further
        details may be found at <ulink
        url="https://01.org/linuxgraphics/downloads/firmware/">01.org</ulink>
        and <ulink
        url="https://wiki.archlinux.org/index.php/intel_graphics">Arch
        linux</ulink>.
      </para>

      <para>
        Nvidia GPUs from Kepler onwards require signed firmware, otherwise the
        nouveau driver is unable to provide hardware acceleration. Nvidia has
        now released firmware up to Ampere (GeForce30 series) to linux-firmware.
        Note that faster clocks than the default are not enabled
        by the released firmware.
      </para>
    </listitem>
    <listitem>
      <para>
        Firmware updates for wired network ports. Mostly they work even
        without the updates, but probably they will work better with
        the updated firmware. For some modern laptops, firmware for both
        wired ethernet (e.g. rtl_nic) and also for bluetooth devices (e.g. qca)
        is <emphasis>required</emphasis> before the wired network can be used.
      </para>
    </listitem>
    <listitem>
      <para>
        Firmware for other devices, such as wifi. These devices are not
        required for the PC to boot, but need the firmware before these devices
        can be used.
      </para>
    </listitem>
  </itemizedlist>

  <note>
    <para>
      Although not needed to load a firmware blob, the following
      tools may be useful for determining, obtaining, or preparing the needed
      firmware in order to load it into the system:
      <xref linkend="cpio"/>,
      <xref linkend="git"/>,
      <xref linkend="pciutils"/>, and
      <xref linkend="wget"/>
    </para>
  </note>

  <para condition="html" role="usernotes">User Notes:
  <ulink url="&blfs-wiki;/aboutfirmware"/></para>

  <sect2 id="cpu-microcode">
    <title>Microcode updates for CPUs</title>

    <para>
      In general, microcode can be loaded by the BIOS or UEFI, and it might be
      updated by upgrading to a newer version of those. On linux, you can also
      load the microcode from the kernel if you are using an AMD family 10h or
      later processor (first introduced late 2007), or an Intel processor from
      1998 and later (Pentium4, Core, etc), if updated microcode has been
      released. These updates only last until the machine is powered off, so
      they need to be applied on every boot.
    </para>

    <para>
      Intel provide updates of their microcode for Skylake and later
      processors as new vulnerabilities come to light, and have in the past
      provided updates for processors from SandyBridge onwards, although those
      are no-longer supported for new fixes. New versions of AMD
      firmware are rare and usually only apply to a few models, although
      motherboard manufacturers get AGESA (AMD Generic Encapsulated Software
      Architecture) updates to change BIOS values, e.g. to support more memory
      variants or newer CPUs.
    </para>

    <para>
      There were two ways of loading the microcode, described as 'early' and
      'late'. Early loading happens before userspace has been started, late
      loading happens after userspace has started. However, late loading is
      known to be problematic and not supported anymore (see the kernel commit
      <ulink url="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d23d33e">
        x86/microcode: Taint and warn on late loading</ulink>.)  Indeed, early
      loading is needed to work around one particular erratum in early Intel
      Haswell processors which had TSX enabled.  (See <ulink url=
      "http://www.anandtech.com/show/8376/intel-disables-tsx-instructions-erratum-found-in-haswell-haswelleep-broadwellyi/">
        Intel Disables TSX Instructions: Erratum Found in Haswell,
        Haswell-E/EP, Broadwell-Y</ulink>.)
      Without this update glibc can do the wrong thing in uncommon
      situations.
    </para>

    <para>
      In previous versions of this book, late loading of microcode to see if
      it gets applied was recommended, followed by using an initrd to force
      early loading. But now that the contents of the Intel microcode tarball
      is documented, and AMD microcode can be read by a Python script to
      determine which machines it covers, there is no real reason to use late
      loading.
    </para>

    <para>
      It might be still possible to manually force late loading of microcode.
      But it may cause kernel malfunction and you should take the risk yourself.
      You will need to reconfigure your kernel for either method. The
      instructions here will show you how to create an initrd for early
      loading. It is also possible to build the same microcode bin file into
      the kernel, which allows early loading but requires the kernel to be
      recompiled to update the microcode.
    </para>

    <para>
      To confirm what processor(s) you have (if more than one, they will be
      identical) look in /proc/cpuinfo. Determine the decimal values of the cpu
      family, model and stepping by running the following command (it will also
      report the current microcode version):
    </para>

<screen><userinput>head -n7 /proc/cpuinfo</userinput></screen>

    <para>
      Convert the cpu family, model and stepping to pairs of hexadecimal
      digits, and remember the value of the <quote>microcode</quote> field.
      You can now check if there is any microcode available.
    </para>

    <para>
      If you are creating an initrd to update firmware for different machines,
      as a distro would do, go down to 'Early loading of microcode' and cat all
      the Intel blobs to GenuineIntel.bin or cat all the AMD blobs to
      AuthenticAMD.bin. This creates a larger initrd - for all Intel machines in
      the 20200609 update the size was 3.0 MB compared to typically 24 KB for one
      machine.
    </para>

    <sect3 id="intel-microcode">
      <title>Intel Microcode for the CPU</title>

      <para>
        The first step is to get the most recent version of the Intel
        microcode.  This must be done by navigating to <ulink url=
        'https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/releases/'/>
        and downloading the latest file there.  As of this writing the most
        <!-- at one time, some skylakes had problems with a certain revision
        secure version of the microcode, for those machines which can boot it, -->
        secure version of the microcode
        is microcode-20220510.<!-- If you have a Skylake machine, please read the
        Caution in the 'Early loading of microcode' section below.-->  Extract this
        file in the normal way, the microcode is in the <filename>intel-ucode
        </filename> directory, containing various blobs with names in the form
        XX-YY-ZZ. There are also various other files, and a releasenote.
      </para>

      <para>
        In the past, intel did not provide any details of which blobs had
        changed versions, but now the releasenote details this.  You can
        compare the microcode version in <filename>/proc/cpuinfo</filename>
        with the version for your CPU model in the releasenote to know if
        there is an update.
      </para>

      <para>
        The recent firmware for older processors is provided to deal with
        vulnerabilities which have now been made public, and for some of these
        such as Microarchitectural Data Sampling (MDS) you might wish to
        increase the protection by disabling hyperthreading, or alternatively
        to disable the kernel's default mitigation because of its impact on
        compile times. Please read the online documentation at <ulink url=
        'https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/index.html'/>.
      </para>

      <para>
        For an Icelake mobile (described as Intel(R) Core(TM) i7-1065G7
        CPU) the relevant values are cpu family 6, model 126, stepping 5 so
        in this case the required identification is 06-7e-05. The
        releasenote says the latest microcode for it is versioned 0xb0.  If
        the value of the <quote>microcode</quote> field in
        <filename>/proc/cpuinfo</filename> is 0xb0 or greater, it indicates
        the microcode update is already applied by the BIOS.  Otherwise,
        configure the kernel to support loading Intel microcode, and then
        proceed to <xref linkend='early-microcode'/>:
      </para>

<screen><literal>General Setup ---&gt;
  [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support [CONFIG_BLK_DEV_INITRD]
Processor type and features  ---&gt;
  [*] CPU microcode loading support  [CONFIG_MICROCODE]
  [*]      Intel microcode loading support [CONFIG_MICROCODE_INTEL]</literal></screen>

    </sect3>

    <sect3 id="amd-microcode">
      <title>AMD Microcode for the CPU</title>

      <para>
        Begin by downloading a container of firmware for your CPU family
        from <ulink url=
          '&sources-anduin-http;/linux-firmware/amd-ucode/'/>.
        The family is always specified in hex. Families 10h to 14h (16 to 20)
        are in microcode_amd.bin.  Families 15h, 16h, 17h (Zen, Zen+, Zen2) and
        19h (Zen3) have their own containers.  Very few machines are likely to
        get updated microcode. There is a Python3 script at <ulink url=
        'https://github.com/AMDESE/amd_ucode_info/blob/master/amd_ucode_info.py'/>.
        Download that script and run it against the bin file to check which
        processors have updates.
      </para>

      <para>
        For the very old Athlon(tm) II X2 in these examples the values were
        cpu family 16, model 5, stepping 3 giving an identification of
        Family=0x10 Model=0x05 Stepping=0x03.  One line of the
        <command>amd_ucode_info.py</command> script output describes the
        microcode version for it:
      </para>

<screen><computeroutput>Family=0x10 Model=0x05 Stepping=0x03: Patch=0x010000c8 Length=960 bytes</computeroutput></screen>

      <para>
        If the value of the <quote>microcode</quote> field in
        <filename>/proc/cpuinfo</filename> is 0x10000c8 or greater, it
        indicates the BIOS has already applied the microcode update.
        Otherwise, configure the kernel to support loading AMD microcode,
        and then proceed to <xref linkend='early-microcode'/>:
      </para>

<screen><literal>General Setup ---&gt;
  [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support [CONFIG_BLK_DEV_INITRD]
Processor type and features  ---&gt;
  [*] CPU microcode loading support  [CONFIG_MICROCODE]
  [*]      AMD microcode loading support [CONFIG_MICROCODE_AMD]</literal></screen>
    </sect3>

    <sect3 id="early-microcode">
      <title>Early loading of microcode</title>

      <para>
        If you have established that updated microcode is available for
        your system, it is time to prepare it for early loading. This requires
        an additional package, <xref linkend='cpio'/> and the creation of an
        initrd which will need to be added to grub.cfg.
      </para>

      <para>
        It does not matter where you prepare the initrd, and once it is
        working you can apply the same initrd to later LFS systems or newer
        kernels on this same machine, at least until any newer microcode is
        released. Use the following commands:
      </para>

<screen><userinput>mkdir -p initrd/kernel/x86/microcode
cd initrd</userinput></screen>

      <para>
        For an AMD machine, use the following command (replace
        &lt;MYCONTAINER&gt; with the name of the container for your CPU's
        family):
      </para>

<screen><userinput>cp -v /lib/firmware/amd-ucode/&lt;MYCONTAINER&gt; kernel/x86/microcode/AuthenticAMD.bin</userinput></screen>

      <para>
        Or for an Intel machine copy the appropriate blob using this command:
      </para>

<screen><userinput>cp -v /lib/firmware/intel-ucode/&lt;XX-YY-ZZ&gt; kernel/x86/microcode/GenuineIntel.bin</userinput></screen>

<!-- new version from 20201110 release onwards, assumed to work on all skylakes
   But complaints about previous version took some days to appear, so keep as a comment for now.
      <caution>
        <para>
          On some Skylake machines with hex Model Number '4e' (78 decimal) the
          upgrade to microcode version '0xdc' is reported to cause the machine to
          hang in early boot, and the fix is to revert to version 0xd6 which was
          first shipped in the 20191115 microcode release.
        </para>

        <para>
          At least one model '5e' Skylake does boot successfully with version
          0xdc, but Intel has now shipped a 20200616 release which is intended for
          distros which need an initrd that will boot on everyone's machine: it
          reverts both Skylake variants ('4e' and '5e') to the old 0xd6.
        </para>

        <para>
          For a Skylake which does not boot with 0xdc, reverting to 0xd6 will make
          the machine usable, but without the SRBDS mitigations.
        </para>
      </caution>-->

      <para>
        Now prepare the initrd:
      </para>

<screen><userinput>find . | cpio -o -H newc &gt; /boot/microcode.img</userinput></screen>

      <para>
        You now need to add a new entry to /boot/grub/grub.cfg and
        here you should add a new line after the linux line within the stanza.
        If /boot is a separate mountpoint:
       </para>

<screen><userinput>initrd /microcode.img</userinput></screen>

      <para>
        or this if it is not:
      </para>

<screen><userinput>initrd /boot/microcode.img</userinput></screen>

      <para>
        If you are already booting with an initrd (see <xref
        linkend="initramfs"/>), you should run <command>mkinitramfs</command>
        again after putting the appropriate blob or container into <filename
        class="directory">/lib/firmware</filename> as explained above.
        Alternatively, you can have both initrd on the same line, such as
        <userinput>initrd /microcode.img /other-initrd.img</userinput> (adapt
        that as above if /boot is not a separate mountpoint).
      </para>

      <para>
        You can now reboot with the added initrd, and then use the same
        command to check that the early load worked:
      </para>

<screen><userinput>dmesg | grep -e 'microcode' -e 'Linux version' -e 'Command line'</userinput></screen>

      <para>
        If you updated to address vulnerabilities, you can look at the
        output of the <command>lscpu</command> command to see what is now
        reported.
      </para>

      <para>
        The places and times where early loading happens are very different
        in AMD and Intel machines. First, an example of an Intel (Icelake
        mobile) with early loading:
      </para>

<screen><literal>[    0.000000] microcode: microcode updated early to revision 0xb0, date = 2022-03-09
[    0.000000] Linux version 5.18.1 (xry111@xry111-X57S1) (gcc (GCC) 12.1.0, GNU ld (GNU Binutils) 2.38) #95 SMP PREEMPT_DYNAMIC Sun Jun 5 21:14:29 CST 2022
[    0.000000] Command line: BOOT_IMAGE=/vmlinuz-5.18.1-lfs-r11.1-109-systemd root=/dev/nvme0n1p7 ro
[    0.435085] microcode: sig=0x706e5, pf=0x80, revision=0xb0
[    0.435197] microcode: Microcode Update Driver: v2.2.</literal></screen>


      <para>
        A historic AMD example:
      </para>

<screen><literal>[    0.000000] Linux version 4.15.3 (ken@testserver) (gcc version 7.3.0 (GCC))
               #2 SMP Sun Feb 18 02:32:03 GMT 2018
[    0.000000] Command line: BOOT_IMAGE=/vmlinuz-4.15.3-sda5 root=/dev/sda5 ro
[    0.307619] microcode: microcode updated early to new patch_level=0x010000c8
[    0.307678] microcode: CPU0: patch_level=0x010000c8
[    0.307723] microcode: CPU1: patch_level=0x010000c8
[    0.307795] microcode: Microcode Update Driver: v2.2.</literal></screen>

    </sect3>

  </sect2>

  <sect2 id="video-firmware">
    <title>Firmware for Video Cards</title>

    <sect3 id="ati-video-firmware">
      <title>Firmware for ATI video chips (R600 and later)</title>

      <para>
        These instructions do NOT apply to old radeons before the R600
        family. For those, the firmware is in the kernel's <filename
        class='directory'>/lib/firmware/</filename> directory. Nor do they
        apply if you intend to avoid a graphical setup such as Xorg and are
        content to use the default 80x25 display rather than a framebuffer.
      </para>

      <para>
        Early radeon devices only needed a single 2K blob of firmware. Recent
        devices need several different blobs, and some of them are much bigger.
        The total size of the radeon firmware directory is over 500K &mdash;
        on a large modern system you can probably spare the space, but it is
        still redundant to install all the unused files each time you build
        a system.
      </para>

      <para>
        A better approach is to install <xref linkend='pciutils'/> and then
        use <userinput>lspci</userinput> to identify which VGA controller is
        installed.
      </para>

      <para>
        With that information, check the RadeonFeature page of the Xorg wiki
        for <ulink url="http://wiki.x.org/wiki/RadeonFeature/#index5h2">Decoder
        ring for engineering vs marketing names</ulink> to identify the family
        (you may need to know this for the Xorg driver in BLFS &mdash;
        Southern Islands and Sea Islands use the radeonsi driver) and the
        specific model.
      </para>

      <para>
        Now that you know which controller you are using, consult the
        <ulink url="https://wiki.gentoo.org/wiki/Radeon#Firmware">
           Radeon</ulink> page of the Gentoo wiki which has a table listing
        the required firmware blobs for the various chipsets. Note that
        Southern Islands and Sea Islands chips use different firmware for
        kernel 3.17 and later compared to earlier kernels. Identify and
        download the required blobs then install them:
      </para>

<screen><userinput>mkdir -pv /lib/firmware/radeon
cp -v &lt;YOUR_BLOBS&gt; /lib/firmware/radeon</userinput></screen>

      <para>
        There are actually two ways of installing this firmware. BLFS, in the
        'Kernel Configuration for additional firmware' section part of the
        <xref linkend="xorg-ati-driver"/> section gives an example of
        compiling the firmware into the kernel - that is slightly faster to
        load, but uses more kernel memory. Here we will use the alternative
        method of making the radeon driver a module. In your kernel config
        set the following:
      </para>

<screen><literal>Device Drivers ---&gt;
  Graphics support ---&gt;
      Direct Rendering Manager ---&gt;
        [*] Direct Rendering Manager (XFree86 ... support)  [CONFIG_DRM]
      [M] ATI Radeon                                        [CONFIG_DRM_RADEON]</literal></screen>

      <para>
        Loading several large blobs from /lib/firmware takes a noticeable
        time, during which the screen will be blank. If you do not enable the
        penguin framebuffer logo, or change the console size by using a bigger
        font, that probably does not matter. If desired, you can slightly
        reduce the time if you follow the alternate method of specifying 'y'
        for CONFIG_DRM_RADEON covered in BLFS at the link above &mdash; you
        must specify each needed radeon blob if you do that.
      </para>

    </sect3>

    <sect3 id="amdgpu-video-firmware">
      <title>Firmware for AMD/ATI amdgpu video chips</title>

      <para>
        All video controllers using the amdgpu kernel driver require firmware,
        whether you will be using the xorg amdgpu driver, the xserver's modesetting
        driver, or just kernel modesetting to get a console framebuffer larger than
        80x25.
      </para>

      <para>
        Install <xref linkend="pciutils"/> and use that to check the model name
        (look for 'VGA compatible controller:'). If you have an APU (Accelerated
        Processing Unit, i.e. CPU and video on the same chip) that will probably
        tell you the name. If you have a separate amdgpu video card you will need
        to search to determine which name it uses (e.g. a card described as
        Advanced Micro Devices, Inc. [AMD/ATI] Baffin [Radeon RX 550 640SP / RX
        560/560X] needs Polaris11 firmware.  There is a table of "Family, Chipset
        name, Product name and Firmware" at the end of the Kernel sections in
        <ulink url="https://wiki.gentoo.org/wiki/AMDGPU#Known_firmware_blobs">
        AMDGPU</ulink> page of the Gentoo wiki.
    </para>

    <para>
      Once you have identified the firmware name, install all the relevant
      files for it. For example, the Baffin card mentioned above has 21 different
      polaris11* files, APUs such as renoir and picasso have at least 12 files and
      might gain more in future updates (e.g. the raven APU now has a 13th file,
      raven_ta.bin).
    </para>

<screen><userinput>mkdir -pv /lib/firmware/amdgpu
cp -v &lt;YOUR_BLOBS&gt; /lib/firmware/amdgpu</userinput></screen>

    <para>
      If disk space is not a problem, you could install all the current amdgpu
      firmware files and not worry about exactly which chipset is installed.
    </para>

    <para>
      Building the kernel amdgpu driver as a module is recommended.
      In your kernel .config set at least the following options and review
      the other AMDGPU options according to your target hardware,
      for example "ACP (Audio Co-Processor) Configuration":
    </para>

<screen><literal>Device Drivers ---&gt;
  Graphics support ---&gt;
      Direct Rendering Manager ---&gt;
        [*] Direct Rendering Manager (XFree86 ... support)  [CONFIG_DRM]
        [M] AMD GPU                                         [CONFIG_DRM_AMDGPU]
        Display Engine Configuration ---&gt;
          [*] AMD DC - Enable new display engine (NEW)      [CONFIG_DRM_AMD_DC]</literal></screen>

      <para>
        As written above at the end of the section on 'Firmware for ATI video
        chips', loading large blobs from /lib/firmware can take a noticeable
        time during which the screen will be blank. On a slow machine you might
        wish to refer to the 'Kernel Configuration for additional firmware'
        part of <xref linkend="xorg-amdgpu-driver"/> and compile all the
        required modules into the kernel to reduce this time, at the cost of
        using more kernel memory.
      </para>

    </sect3>

    <sect3 id="nvidia-video-firmware">
      <title>Firmware for Nvidia video chips</title>

      <para>
        Nvidia has released basic signed firmware for recent graphics chips,
        but significantly after the chips and its own binary drivers were first
        available. For other chips it has been necessary to extract the firmware
        from the binary driver.
      </para>
      <para>
        For more exact information about which chips need extracted firmware, see
        <ulink url=
          "https://nouveau.freedesktop.org/wiki/VideoAcceleration/#firmware"/>.
      </para>

      <para>
        First, the kernel Nvidia driver must be activated:
      </para>

<screen><literal>Device Drivers ---&gt;
  Graphics support ---&gt;
      Direct Rendering Manager ---&gt;
        &lt;*&gt; Direct Rendering Manager (XFree86 ... support)  [CONFIG_DRM]
      &lt;*/M&gt; Nouveau (NVIDIA) cards                          [CONFIG_DRM_NOUVEAU]</literal></screen>

      <para>
        If the necessary firmware is available in the
        <filename class="directory">nvidia/</filename> directory of
        linux-firmware, copy it to
        <filename class="directory">/lib/firmware/nouveau</filename>.
      </para>
      <para>
        If the firmware has not been made available in linux-firmware,
        for the old chips mentioned in the nouveau wiki link above ensure you have
        installed <xref linkend="python2"/> and run the following commands:
      </para>

<screen><userinput>wget https://raw.github.com/imirkin/re-vp2/master/extract_firmware.py
wget http://us.download.nvidia.com/XFree86/Linux-x86/325.15/NVIDIA-Linux-x86-325.15.run
sh NVIDIA-Linux-x86-325.15.run --extract-only
python2 extract_firmware.py
mkdir -p /lib/firmware/nouveau
cp -d nv* vuc-* /lib/firmware/nouveau/</userinput></screen>

    </sect3>
  </sect2>

  <sect2 id="nic-firmware">
    <title>Firmware for Network Interfaces</title>

    <para>
      The kernel likes to load firmware for some network drivers, particularly
      those from Realtek (the /lib/linux-firmware/rtl_nic/) directory, but
      they generally appear to work without it. Therefore, you can boot the
      kernel, check dmesg for messages about this missing firmware, and if
      necessary download the firmware and put it in the specified directory in
      <filename class="directory">/lib/firmware</filename> so that it will
      be found on subsequent boots. Note that with current kernels this
      works whether or not the driver is compiled in or built as a module,
      there is no need to build this firmware into the kernel.
      Here is an example where the R8169 driver has been compiled in but the
      firmware was not made available. Once the firmware had been provided,
      there was no mention of it on later boots.
    </para>

<screen><literal>dmesg | grep firmware | grep r8169
[    7.018028] r8169 0000:01:00.0: Direct firmware load for rtl_nic/rtl8168g-2.fw failed with error -2
[    7.018036] r8169 0000:01:00.0 eth0: unable to load firmware patch rtl_nic/rtl8168g-2.fw (-2)</literal></screen>

  </sect2>

  <sect2 id="other-firmware">
    <title>Firmware for Other Devices</title>

    <para>
      Identifying the correct firmware will typically require you to install
      <xref linkend='pciutils'/>, and then use <userinput>lspci</userinput>
      to identify the device. You should then search online to check which
      module it uses, which firmware, and where to obtain the firmware &mdash;
      not all of it is in linux-firmware.
    </para>

    <para>
      If possible, you should begin by using a wired connection when you first
      boot your LFS system. To use a wireless connection you will need to
      use a network tools such as <xref linkend='wireless_tools'/> and <xref
      linkend='wpa_supplicant'/>.
    </para>

    <para>
      Different countries have different regulations on the radio spectrum
      usage of wireless devices.  You can install a firmware to make the
      wireless devices obey local spectrum regulations, so you won't be
      inquired by local authority or find your wireless NIC jamming the
      frequencies of other devices (for example, remote controllers).
      The regulatory database firmware can be downloaded from
      <ulink url = 'https://kernel.org/pub/software/network/wireless-regdb/'/>.
      To install it, simply extract <filename>regulatory.db</filename> and
      <filename>regulatory.db.p7s</filename> from the tarball into
      <filename class="directory">/lib/firmware</filename>.
      The access point would send a country code to your wireless NIC,
      and <xref linkend='wpa_supplicant'/> would tell the kernel to load
      the regulation of this country from
      <filename>regulatory.db</filename>, and enforce it.
    </para>

    <para>
      Firmware may also be needed for other devices such as some SCSI
      controllers, bluetooth adaptors, or TV recorders. The same principles
      apply.
    </para>

  </sect2>

</sect1>