path: root/doc/genkernel.8.txt

GENKERNEL(8)
============
:man source:   genkernel {genkernelversion}
:man manual:   genkernel {genkernelversion}


NAME
----
genkernel - the Gentoo Linux automatic kernel compiler.


SYNOPSIS
--------
*genkernel* [options...] action


INTRODUCTION
------------
Genkernel is designed to allow users who are not previously used to
compiling a kernel to use a similar setup to that one that is used on
the Gentoo LiveCDs which auto-detects your hardware.

Some users may also be interested in using genkernel for hardware which
requires initialization and a working kernel before it can be booted
because genkernel also automatically compiles your kernel modules,
allowing hardware which needs to be loaded with module parameters to be
used.


USAGE
-----
All that is needed to run genkernel is just `genkernel` with an
action and any flags you might need:

------------------------------------------
# genkernel --menuconfig --no-clean --no-install all
------------------------------------------

This would produce a kernel, asking you what how to configure it to
your desire, leaving alone any existing compiled object files, but not
installing anything.


ACTIONS
-------
An action tells genkernel what you want it to do  -  the following
actions are supported:

*all*::
    Build all steps - the kernel, modules, and the ramdisk.
*bzImage*::
    Build only the kernel.
*initramfs*::
    Build only the ramdisk/initramfs.
*kernel*::
    Build only the kernel and the modules.
*ramdisk*::
    Build only the ramdisk/initramfs.


OPTIONS
-------
Genkernel supports the following options which alter its behaviour.
Certain options have *--no-* variants which do the opposite thing.
You can specify your options in any order.


CONFIGURATION OPTIONS
~~~~~~~~~~~~~~~~~~~~~
*--config*=<file>::
    Genkernel configuration file to use.


DEBUGGING OPTIONS
~~~~~~~~~~~~~~~~~
*--loglevel*=<0-5>::
    This controls the out verbosity level of genkernel output - if
    this is set to 0, minimal debugging is done; if this is set to 5
    as much output as possible is given.

*--logfile*=<outfile>::
    This outputs debugging data to the file <outfile>. By default
    this is '/var/log/genkernel.log'.

*--*[*no-*]*color*::
    Turns on, or off, output in color using escape sequences.

*--*[*no-*]*cleanup*::
    Turns on or off the full post-run cleanup for debug purposes.


KERNEL CONFIGURATION
~~~~~~~~~~~~~~~~~~~~
*--*[*no-*]*menuconfig*::
    Runs, or does not run "make menuconfig" after running "make oldconfig".

*--*[*no-*]*nconfig*::
    Runs, or does not run "make nconfig" after running "make oldconfig".

*--*[*no-*]*gconfig*::
    Runs, or does not run "make gconfig" after "make oldconfig".

*--*[*no-*]*xconfig*::
    Runs, or does not run "make xconfig" after "make oldconfig".

*--*[*no-*]*save-config*::
    Saves, or does not save the kernel configuration to '/etc/kernels'
    if the kernel is successfully compiled.

*--*[*no-*]*bcache*::
    Adds, or skip adding block layer cache (bcache) support to kernel
    configuration.

*--*[*no-*]*hyperv*::
    Adds, or skip adding Microsoft Hyper-V support to kernel configuration.

*--microcode*[=<all|amd|intel>]::
    Adds early microcode loading support for all, only AMD or Intel processors
    to kernel configuration.

*--no-microcode*::
    Do not add early microcode loading support to kernel configuration.

*--*[*no-*]*virtio*::
    Adds, or skip adding VirtIO support to kernel configuration.

*--kernel-append-localversion*=<...>::
    Appends value to genkernel's *KERNEL_LOCALVERSION* option (see below).
    The idea is to use this option to allow to easily build a new revision
    with own kernel binary, initramfs and modules directory without losing
    default *KERNEL_LOCALVERSION* value.

*--kernel-localversion*=<...>::
Set kernel option *LOCALVERSION*. Use special value *UNSET* to
unset any already set *LOCALVERSION*. The following placeholders are
available:
+
[horizontal]
*%%ARCH%%*:::
Will be replaced with genkernel arch value, for example 'x86_64'.

+
*LOCALVERSION* is only allowed to contain characters like 'a-z' or 'A-Z',
'0-9', '_', '.' and '-'.
+
By default, *LOCALVERSION* will be set to '-%%ARCH%%'.


KERNEL COMPILATION
~~~~~~~~~~~~~~~~~~
*--*[*no-*]*clean*::
    Runs, or does not run, "make clean" before compilation  -  this
    erases any compiled object files in the kernel source tree but
    does not have an impact on the kernel configuration.  Specifying
    *--no-clean* implies *--no-mrproper*.

*--*[*no-*]*mrproper*::
    Runs, or does not run, "make mrproper" before compilation - this
    erases both any compiled object files in the kernel source tree
    as well as the kernel configuration.

*--*[*no-*]*install*::
    Installs,  or does not install the kernel to '/boot' after building.
    The default is  *--install*.   If MOUNTBOOT is set in
    '/etc/genkernel.conf'  then '/boot' will be automatically mounted if
    it is not already mounted before the ramdisk and kernel images
    are copied over.

*--*[*no-*]*symlink*::
Manages,  or does not manage, symlinks in '/boot' like the manual
kernel "make install" process does. A 'kernel' (or, depending on
options, 'kernelz') symlink will link to the most recently built
kernel image and a 'kernel.old' (or 'kernelz.old') symlink will link
to the second most recently built image, if one exists. Similar
symlinks (with and without '.old' suffix) are managed for initramfs and
System.map. The corresponding work products (i.e., the actual kernel
and initramfs images, and System.map) are also managed accordingly.
+
The symlink name can be controlled via *--kernel-symlink-name* and/or
*--initramfs-symlink-name* option.

NOTE: Specifying *--symlink* does nothing unless *--install* is also
specified.

*--*[*no-*]*oldconfig*::
    Runs, or does not run, "make oldconfig" before compilation.  Specifying
    *--oldconfig* implies *--no-clean*.

*--*[*no-*]*splash*::
    Installs, or not, framebuffer splash support into initramfs.

*--*[*no-*]*ramdisk-modules*::
    Copies or does not copy configured modules to the ramdisk.

*--*[*no-*]*all-ramdisk-modules*::
    Copies or does not copy all kernel modules to the initrd.

*--*[*no-*]*module-rebuild*::
    Runs, or does not run "emerge --ignore-default-opts --buildpkg=n --usepkg=n --quiet-build=y @module-rebuild"
    to build out-of-tree modules when possible, i.e. when non-static
    kernel and modules will be build, installed, no custom
    'INSTALL_MOD_PATH' is set, '/var/lib/module-rebuild/moduledb' exists
    and is not empty.

NOTE: Command can be customized using '--module-rebuild-cmd' command-line
argument or 'MODULEREBUILD_CMD' in '/etc/genkernel.conf'.

*--module-rebuild-cmd*=<...>::
    Overwrite default *--module-rebuild* command.

*--callback*=<...>::
    Run the specified arguments in the current environment after the
    kernel and modules have been compiled.

*--*[*no-*]*static*::
    Builds, or does not build a monolithic kernel without any modules on
    any initial ramdisks.


KERNEL LOCATIONS
~~~~~~~~~~~~~~~~
*--kerneldir*=<dir>::
    This specifies the location of the kernel sources;  the default
    is '/usr/src/linux'.

*--kernel-config*=<file|default>::
    This specifies a kernel configuration file to use for compilation;
    by default genkernel uses the config from the previous
    build of the same kernel version or a default kernel config if
    there isn't a previous config.
    Use the special value 'default' to force usage of default kernel
    config.

*--module-prefix*=<dir>::
    Prefix to kernel module destination, modules will be installed in
    '<prefix>/lib/modules'.


LOW-LEVEL COMPILATION OPTIONS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*--cross-compile*=<target triplet>::
    Target triple (i.e. aarch64-linux-gnu) to build for. Only needed
    when the system running genkernel has a different architecture like
    the system which should boot the created kernel/initramfs.

*--kernel-as*=<assembler>::
    Assembler to use for the kernel compilation.

*--kernel-cc*=<compiler>::
    Compiler to use for the kernel compilation (e.g. distcc).

*--kernel-ld*=<linker>::
    Linker to use for the kernel compilation.

*--kernel-make*=<makeprg>::
    GNU Make to use for the kernel compilation.

*--kernel-target*=<t>::
    Override default make target (bzImage), note that values
    like *--kernel-target=* are also valid (useful for Xen
    based kernel sources).

*--kernel-binary*=<path>::
    Override default kernel binary path (arch/foo/boot/bar).

*--kernel-outputdir*=<path>::
    Save output files outside the source tree. This should be used rather than
    KBUILD_OUTPUT when you wish to place kernel objects outside of the source
    tree (eg because cannot write to that directory as the user genkernel is
    running as).

*--utils-as*=<assembler>::
    Assembler to use for utilities.

*--utils-cflags*=<cflags>::
    C compiler flags used to compile utilities.

*--utils-cc*=<compiler>::
    C Compiler to use for utilities.

*--utils-cxx*=<compiler>::
    C++ Compiler to use for utilities.

*--utils-ld*=<linker>::
    Linker to use for utilities.

*--utils-make*=<makeprog>::
    GNU Make to use for utilities.

*--makeopts*=<makeopts>::
    GNU Make options such as -j2, etc.

*--*[*no-*]*mountboot*::
    Mount, or not, BOOTDIR automatically if mountable.

*--bootdir*=<dir>::
    Set the location of the boot-directory, default is '/boot'.

*--modprobedir*=<dir>::
    Set the location of the modprobe.d-directory, default is '/etc/modprobe.d'.

*--*[*no-*]*nice*[=<niceness>]::
    Runs the kernel make at the default niceness (reduction in priority) of
    10, or in the case of *--no-nice*, runs the kernel make at normal priority.


INITIALIZATION
~~~~~~~~~~~~~~
*--splash*=<theme>::
    Enable framebuffer splash using <theme>.

*--splash-res*=<resolutions>::
    Select gensplash resolutions to include.

*--*[*no-*]*splash*=<theme>::
    If the extra argument is specified,  splash is forced using
    <theme>  rather than the default theme specified in your splash
    configuration. If *--no-splash* is specified, then splash is disabled.

*--do-keymap-auto*::
    Force keymap selection at boot.

*--*[*no-*]*keymap*::
    Enables or disables keymap selection at boot.

*--*[*no-*]*lvm*::
    Includes or excludes LVM support.
    When enabled, this will compile LVM for you.

*--*[*no-*]*mdadm*::
    Includes or excludes mdadm support.
    When enabled, this will compile mdadm for you.

*--mdadm-config*=<file>::
    Use <file> as configfile for MDADM.
    By default the ramdisk will be built *without* an 'mdadm.conf' and
    will auto-detect arrays during boot-up.

*--*[*no-*]*microcode-initramfs*::
    Prepends, or do not prepend ucode(s) to the initramfs.
    But only when kernel configuration does support early microcode loading.
    See *--microcode* option to auto-update kernel configuration.

NOTE: Embedding microcode updates into initramfs is *deprecated* when
system is able to load multiple initramfs.

*--*[*no-*]*dmraid*::
    Includes or excludes DMRAID support.
    When enabled, this will compile dmraid for you.

*--*[*no-*]*nfs*::
    Includes or excludes NFS support.

*--*[*no-*]*e2fsprogs*::
    Includes or excludes e2fsprogs.
    When enabled, this will compile e2fsprogs for you.

*--*[*no-*]*xfsprogs*::
    Includes or excludes xfsprogs.
    When enabled, this will compile xfsprogs for you.

*--*[*no-*]*zfs*::
    Includes or excludes ZFS support.

*--*[*no-*]*btrfs*::
    Includes or excludes Btrfs support.
    When enabled, this will compile btrfs-progs for you.

*--*[*no-*]*multipath*::
    Includes or excludes Multipath support.
    When enabled, this will compile multipath-tools for you.

*--*[*no-*]*iscsi*::
    Includes or excludes iSCSI support.
    When enabled, this will compile open-iscsi for you.

*--*[*no-*]*sandbox*::
    Enables or disables sandbox-ing when building initramfs.

*--*[*no-*]*ssh*::
    Includes or excludes SSH (dropbear) support for remote LUKS keys.
    When enabled, this will compile dropbear for you.

*--ssh-authorized-keys-file*=<file>::
    Specifies a user created authorized_keys file. By default genkernel
    will use '/etc/dropbear/authorized_keys'.

*--ssh-host-keys*=<create|create-from-host|runtime>::
    When set to *create*, which is the default value, genkernel will embed
    SSH host keys from '/etc/dropbear' and will create those keys when missing.
    When set to *create-from-host*, genkernel will embed SSH host keys from
    '/etc/dropbear' but will create those keys from '/etc/ssh' when missing
    (not recommended for security reasons).
    When set to *runtime*, genkernel will not embed any SSH host key in
    initramfs and dropbear will generate needed host key at runtime (`dropbear -R`).

*--boot-font*=<current|<file>|none>::
    When set to *current*, genkernel will use "setfont" to dump and embed
    current active console font into initramfs.
    When set to a *PC Screen Font file*, genkernel will embed that font
    into initramfs.
    When set to *none*, genkernel will not embed any font file in initramfs.
    In case a font was embedded into initramfs, genkernel will load that
    font early on boot. See *gk.bootfont.disabled* kernel parameter for
    disabling that feature at runtime.

*--bootloader*=<grub|grub2>::
    Add new kernel to GRUB or GRUB2 configuration.

*--linuxrc*=<file>::
    Use <file> for the linuxrc instead of the genkernel linuxrc.

*--busybox-config*=<file>::
    Specifies a user created busybox config.

*--genzimage*::
    Make and install kernelz image from 'arch/powerpc/boot/zImage.initrd'.

*--*[*no-*]*disklabel*::
    Includes or excludes disk label and uuid support in your initramfs.
    When enabled, this will compile util-linux for you.

*--*[*no-*]*luks*::
    Includes or excludes LUKS support.
    When enabled, this will compile cryptsetup for you.

*--*[*no-*]*gpg*::
    Includes or excludes support for GnuPG 1.x, the portable standalone branch
    of GnuPG. A key can be made from
    `gpg --symmetric -o /path/to/LUKS-key.gpg /path/to/LUKS-key` .
    After that, re-point the *root_key* argument to the new .gpg file.

*--*[*no-*]*b2sum*::
    Includes or excludes b2sum in the initramfs.
    When enabled, this will compile coreutils' b2sum for you.

*--*[*no-*]*busybox*::
    Includes or excludes busybox in the initramfs.
    When enabled, this will compile busybox for you.

*--*[*no-*]*unionfs*::
    Includes or excludes support for unionfs.
    When enabled, this will compile unionfs-fuse for you.

*--*[*no-*]*netboot*::
    Creates or does not create a self-contained env in the initramfs.

*--real-root*=<foo>::
    Specify a default for *real_root*= kernel option which will be
    embedded into initramfs.


INTERNALS
~~~~~~~~~
*--cachedir*=<dir>::
    Override the default cache location.

*--check-free-disk-space-bootdir*=<MB>::
    When set to a non-zero value, genkernel will check early on start for
    specified amount of free disk space in megabyte in *BOOTDIR*.

*--check-free-disk-space-kerneloutputdir*=<MB>::
    When set to a non-zero value, genkernel will check early on start for
    specified amount of free disk space in megabyte in *KERNEL_OUTPUTDIR*.

*--*[*no-*]*clear-cachedir*::
    Clears or skips clearing all files in cache location on genkernel start.

*--tmpdir*=<dir>::
    Sets genkernel's temporary working directory to <dir>. By default, a
    directory below '/var/tmp/genkernel' will be used.

*--*[*no-*]*postclear*::
    Clears or skips clearing all tmp files and caches after genkernel has run.


OUTPUT SETTINGS
~~~~~~~~~~~~~~~
*--initramfs-filename*=<...>::
Set initramfs filename which will be used when initramfs will be installed
into *BOOTDIR* (implies *--install* option). Please see
*--kernel-filename* option for available placeholders and restrictions.
+
By default, initramfs filename will be set to 'initramfs-%%KV%%.img'.

*--initramfs-symlink-name*=<...>::
Set initramfs symlink name which will be used when initramfs will be
installed into *BOOTDIR* (implies *--install* option) and *--symlink*
option is given. Please see *--kernel-filename* option for available
placeholders and restrictions.
+
By default, initramfs symlink name will be set to 'initramfs'.

NOTE: Initramfs filename and initramfs symlink name must be different.

*--minkernpackage*=<file>::
Archive file created using tar containing kernel and initramfs.

NOTE: No modules outside of the initramfs will be included!

*--modulespackage*=<archive>::
    Archive file created using tar containing modules after the callbacks
    have run.

*--kerncache*=<archive>::
    Archive file created using tar containing kernel binary, content of
    '/lib/modules' and the kernel config after the callbacks have run.

*--kernel-config-filename*=<...>::
Set the kernel config filename used by *--save-config*. Please see
*--kernel-filename* option for available placeholders and restrictions.
+
By default, kernel config filename will be set to 'kernel-config-%%KV%%'.

*--kernel-filename*=<...>::
Set kernel filename which will be used when kernel will be installed
into *BOOTDIR* (implies *--install* option). The following placeholders
are available:
+
[horizontal]
*%%ARCH%%*:::
Will be replaced with genkernel arch value, for example 'x86_64'.
*%%KV%%*:::
Will be replaced with kernel version, for example '5.2.3-gentoo'.

+
Kernel filename is only allowed to contain characters like 'a-z' or 'A-Z',
'0-9', '_', '.' and '-'.
+
By default, kernel name will be set to 'vmlinuz-%%KV%%'.

NOTE: When setting a custom kernel name make sure that your bootloader and
tools like *kexec* when used are recognizing your custom kernel name.

*--*[*no-*]*kernel-sources*::
    This option is only valid if kerncache is defined If there is a
    valid kerncache no checks will be made against a kernel source
    tree.

*--kernel-symlink-name*=<...>::
Set kernel symlink name which will be used when kernel will be installed
into *BOOTDIR* (implies *--install* option) and *--symlink* option is
given. Please see *--kernel-filename* option for available placeholders
and restrictions.
+
By default, kernel symlink name will be set to 'kernel'.

NOTE: Kernel filename and kernel symlink name must be different.

*--systemmap-filename*=<...>::
Set System.map filename which will be used when kernel will be installed
into *BOOTDIR* (implies *--install* option). Please see
*--kernel-filename* option for available placeholders and restrictions.
+
By default, System.map filename will be set to 'System.map-%%KV%%'.

*--systemmap-symlink-name*=<...>::
Set System.map symlink name which will be used when kernel will be
installed into *BOOTDIR* (implies *--install* option) and *--symlink*
option is given. Please see *--kernel-filename* option for available
placeholders and restrictions.
+
By default, System.map symlink name will be set to 'System.map'.

NOTE: System.map filename and System.map symlink name must be different.

*--initramfs-overlay*=<dir>::
    Directory structure to include in the initramfs, only available
    on >=2.6 kernels.

*--*[*no-*]*firmware*::
    Enable or disables copying of firmware into initramfs.

*--firmware-dir*=<dir>::
    Specify directory to copy firmware from (defaults to '/lib/firmware').

*--firmware-files*=<files>::
    Specifies specific firmware files to copy. This overrides *--firmware-dir*.
    For multiple files, separate the filenames with a comma.

*--*[*no-*]*firmware-install*::
    Enable or disables installation of firmware onto root filesystem.
    Please note this is deprecated, and installing
    *sys-kernel/linux-firmware* should be preferred instead.

*--*[*no-*]*integrated-initramfs*::
    Builds or does not build the generated initramfs into the kernel instead
    of keeping it as a separate file.

*--*[*no-*]*wrap-initrd*::
    Wrap initramfs using mkimage for u-boot boots. Please note that only
    certain compression types are supported by mkimage (see manpage).

*--*[*no-*]*compress-initramfs*::
    Compresses or does not compress the generated initramfs.

*--*[*no-*]*compress-initrd*::
    Deprecated alias for *--*[*no-*]*compress-initramfs*.

*--compress-initramfs-type*=<arg>::
    Compression type for initramfs (best, bzip2, fastest, gzip, lz4, lzma,
    lza, xz, zstd).
+
*best* will select the algorithm providing best compression
from those selected in your kernel configuration.
+
*fastest* will select the algorithm providing fastest decompression
from those selected in your kernel configuration.

*--strip*=<all|kernel|modules|none>::
    Strip debug symbols from none, all, installed kernel (obsolete) or
    modules (default).

*--no-strip*::
    Alias for *--strip=none*.


RAMDISK/INITRAMFS OPTIONS
-------------------------
The following options are some of those available to be passed as kernel
parameters from the bootloader. Genkernel will not handle this
operation, please refer to your bootloader documentation for a more
complete description of each.

This listing is intended to cover most of the options recognized by the
ramdisk/initramfs scripts, as well as some of the common options
recognized by the kernel itself.

*root*=<...>::
    Specifies the device node of the root filesystem to mount.

*real_root*=<...>::
    Legacy kernel parameter from kernel-2.4 initrd.
    Does the same as *root*=, which should be used in its place.

*crypt_root*=<...>::
    This specifies the device encrypted by LUKS, which contains the
    root filesystem to mount.

*crypt_swap*=<...>::
    This specifies the swap device encrypted by LUKS.

*root_key*=<...>::
    In case your root is encrypted with a key, you can use a device
    like a  usb pen to store the key.  This value should be the key
    path relative to the mount point.

*root_keydev*=<...>::
    If necessary provide the name of the device that carries the
    root_key.   If unset while using root_key, it will automatically
    look for the device in every boot.

*root_trim*=(yes|no)::
    Enables TRIM support for a LUKS-based root device.  Only useful
    with SSD setups.  Have a look at 'https://en.wikipedia.org/wiki/TRIM'
    for more information.

*swap_key*=<...>::
    Same as root_key for swap.

*swap_keydev*=<...>::
    Same as root_keydev for swap.

*crypt_silent*::
    Set this to silent all the output related to the cryptographic
    software,  and in case your encrypted device isn't open with the
    key, it opens a shell in the initrd quietly.

*dodmraid*[=<...>]::
    Activate Device-Mapper RAID and (optionally) pass arguments to it.

*init*=<...>::
    Override location of init script, default is "/sbin/init".

*real_init*=<...>::
    Legacy kernel parameter from kernel-2.4 initrd.
    Does the same as *init*=, which should be used in its place.

*init_opts*=<...>::
    Passes arguments to init on bootup.

*scandelay*[=<...>]::
    Pauses for 10 seconds before running devfsd if no argument is
    specified; otherwise pauses for the number of specified seconds.

*rootdelay*[=<...>]::
*rootwait*[=<...>]::
    Pauses for up to 3 seconds (or specified number of seconds) while
    waiting for root device to appear during initramfs root scanning.

*ip*=<dhcp,addr/cidr>::
    Normally used to tell the kernel that it should start a network
    interface which can be specified using *gk.net.iface* kernel parameter.
    By default, dhcp will be used. You can set a specific IP address using
    addr/CIDR notation, i.e. '1.2.3.4/24'.

*gk.net.dhcp.retries*=<...>::
    By default we will send up to 3 DHCP discovery requests.

*gk.net.iface*=<interface,macaddr>::
    By default we will use the interface named eth0. Use this kernel
    parameter to specify another interface. You can also specify a MAC
    address (00:00:00:00:00:00 format) instead of an interface name.

*gk.net.gw*=<...>::
    Optional gateway. If *ip* is set to dhcp, this kernel parameter will
    be ignored.

*gk.net.routes*=<...>::
    Optional additional routes. If *ip* is set to dhcp, this kernel
    parameter will be ignored.

*gk.net.timeout.dad*=<...>::
    By default we will wait up to 10 seconds for IPv6's DAD to complete.
    At the moment, we only wait for DAD while bringing down an interface
    to prevent a race condition.

*gk.net.timeout.deconfiguration*=<...>::
    By default we will wait up to 10 seconds while bringing down an
    interface to prevent a race condition.

*gk.net.timeout.dhcp*=<...>::
    By default we will wait up to 10 seconds for a DHCP server reply.

*gk.net.timeout.interface*=<...>::
    By default we will wait up to 10 seconds for interface to show up.

*gk.udev.timeout*=<...>::
    By default we will wait up to 120 seconds (UDEV default) for
    UDEV event queue to become empty.

*gk.prompt.timeout*=<...>::
By default a prompt within genkernel initramfs like shown when set
*root* could not be found will never timeout. Use this option to set
a timeout.

NOTE: When *dosshd* is used, *gk.prompt.timeout* will be set to 30 seconds
when not set. This will allow remote user to provide answer through
*GK_PROMPT_FILE* which is set to '/tmp/current_prompt' by default.

*dosshd*::
    Will bring up an interface and start a SSH daemon within initramfs
    allowing to remotely unlock encrypted devices or just for debugging
    purpose. See *ip* option for how to configure network.

*gk.sshd.port*=<...>::
    By default, sshd will listen on port 22.

*gk.sshd.wait*=<...>::
    Wait X seconds after setting up sshd, useful when you want to login
    (and thus pause boot process) before booting real system.

*nfsroot*=<...>::
    If present,  the initrd will try to mount a livecd from that
    location. Otherwise the location will be deduced from the DCHP
    request (option root-path).

*dolvm*::
    Activate LVM volumes on bootup.

*lvmraid*=<...>::
    Specify RAID devices to set up before the activation of LVM volumes.
    Implies option *dolvm*.

*domdadm*::
    Scan for RAID arrays on bootup.

*dozfs*[=cache,force]::
    Scan for bootable ZFS pools on bootup. Optionally use cachefile or force import if
    necessary or perform both actions.

*dobtrfs*::
    Scan for attached Btrfs devices on bootup.

*domultipath*::
    Activate Multipath on bootup.

*doscsi*::
    Activate SCSI devices on bootup, necessary when SCSI support is
    compiled as modules and you're using SCSI or SATA devices.

*keymap*='MAP'::
    Set keymap to 'MAP', e.g. *keymap*=de.
    For valid values of 'MAP' please see
    '/usr/share/genkernel/defaults/keymaps/'.

*dokeymap*::
    Use keymap.  Usage of *keymap*= implies this option, already.

*rootfstype*=<...>::
    Specify the file system type to mount the real root filesystem as.
    This can be useful when support for ext2/ext3/ext4 are
    in competition.  Default is "auto".

*docache*::
*nocache*::
    Enables/disables caching of CD contents in RAM.

*subdir*=<...>::
    switch_root into "<CHROOT>/<SUBDIR>" instead of "<CHROOT>/".
    <CHROOT> is "/newroot" (or "/union") usually.

*quiet_genkernel*::
    Do not print anything but error and warning messages during
    the execution of the initramfs init scripts.

*quiet*::
    Implies *quiet_genkernel*, but also recognized by the kernel to
    suppress kernel messages.

*debug*::
    Drop into a debug shell early in the process.

*gk.bootfont.disabled*=<...>::
    By default, if a bootfont is embedded within initramfs, genkernel
    will load that font. This boolean option allows you to disable
    loading of the user embedded bootfont.

*gk.hw.load-all*=<...>::
    By default, genkernel loads various module groups (nvme, sata,
    scsi, pata, usb...) until block device specified in *root* parameter
    becomes available. This boolean option allows you to force
    loading of all module groups regardless whether root device is
    already available.

*gk.log.disabled*=<...>::
    By default, any shown message and external command calls will be logged
    to '/tmp/init.log' in initramfs. This boolean option allows you to
    disable logging for some reason.

*gk.log.keep*=<...>::
When set to a boolean value, genkernel will preserve '/tmp/init.log',
see above, and copy file to '/genkernel-boot.log' on *root* device.
You can also set your own file like '/root/my-genkernel-boot.log' to
copy log to a custom path.

NOTE: The default file '/genkernel-boot.log' on *root* was chosen because
genkernel's initramfs will only mount root filesystem by default. If you
want to store the log file in '/var/log/genkernel-boot.log' for example
make sure that this mountpoint is accessible, see *initramfs.mounts*.

*gk.userinteraction.disabled*=<...>::
By default, genkernel will prompt on errors. In case this is not wanted
or desired, e.g. for a kiosk system, this boolean option will disable
any prompting, including the rescue shell.

NOTE: Because no user interaction is possible when this option is set,
system will automatically reboot on error after a timeout.

*noload*=<...>::
    List of modules to skip loading.
    Separate using commas or spaces.

*nodetect*::
    Skipping scanning modules using "modprobe <MODULE> -n".
    Use *doload=* for specifying a whitelist of exceptions.

*doload*=<...>::
    List of modules to load despite *nodetect*.

*domodules*::
*nomodules*::
    Enables/disables loading of modules in general.

*CONSOLE*=<...>::
*console*=<...>::
    Override location of console, default is "/dev/console".

*part*[=<0,1>]::
*partitionable*::
    Enable/Disable partitionable RAIDs (metadata 0.x) during auto-run.
    Standalone *part* and *partitionable* keywords for kernel compatability.

*iscsi_initiatorname*=<...>::
*iscsi_target*=<...>::
*iscsi_tgpt*=<...>::
*iscsi_address*=<...>::
*iscsi_port*=<...>::
*iscsi_username*=<...>::
*iscsi_password*=<...>::
*iscsi_username_in*=<...>::
*iscsi_password_in*=<...>::
*iscsi_debug*=<...>::
*iscsi_noibft*::
    Specify iSCSI parameters.

*unionfs*::
*nounionfs*::
    Enables/disables UnionFS.

*aufs*::
    Enables support for AUFS (if available in the kernel).

*aufs.modules*=<...>::
    Use an alternate location for filesystem overlays to be added on top of
    the livecd and below the writable tmpfs.  Default is /modules/.

*overlayfs*::
    Enables support for Overlayfs (if available in the kernel).

*overlayfs.modules*=<...>::
    Use an alternate location for filesystem overlays to be added on top of
    the livecd and below the writable tmpfs.  Default is /modules/

*rootflags*=<...>::
    Additional flags to mount the real root system with.
    For example *rootflags*=noatime would make "-o ro,noatime".

*real_rootflags*=<...>::
    Legacy kernel parameter from kernel-2.4 initrd.
    Does the same as *rootflags*=, which should be used in its place.

*real_resume*=<...>::
*resume*=<...>::
*noresume*::
    *noresume* disables any default resume parameters. *resume* and
    *real_resume* specify a device via LABEL or UUID to use for for loading a
    TuxOnICE, SWSUSP or Suspend2 resume image.

*cdroot*[=<...>]::
*cdroot_type*=<...>::
*cdroot_marker*=<...>::
    Used for LiveCDs. *cdroot* without arguments will cause the initramfs to
    scan all devices for a LiveCD. An argument to *cdroot* will cause it to
    scan only that device. A LiveCD is any device containing a file with the
    name & Path of *cdroot_marker* (default of "/livecd"). *cdroot_type*
    (default of "auto") is the filesystem type to use while mounting devices
    to check. On success, the LiveCD will be mounted at $CDROOT_PATH.

*loop*=<...>::
*looptype*=<...>::
    Used for LiveCDs. After mounting the LiveCD or ISO, look for a file at
    *loop*=path to use as a loopback image for the main type. Mount it with
    filesystem type *looptype*. Possible values for *looptype*: normal,
    squashfs, gcloop, zisofs, noloop, sgimips. If *looptype* is not specified,
    a guess is made, based on the name or extension of *loop*.

*isoboot*=<...>::
    Loop-mount an ISO file from the boot device to get the filesystem image.
    Useful with chain-loading environments and USB keys.

initramfs.mounts
----------------
By default, genkernel's initramfs will only mount *root* device. But
sometimes additional mounts are required before initramfs can switch to
real root (for example on systems with a seperate '/usr' mount).

Therefore genkernel package contains '/etc/initramfs.mounts' file which
will allow you to specify additional mounts which should be mounted before
initramfs will switch to real root.

NOTE: This file will not be included in initramfs. Instead, booted initramfs
will check for this file on specified *root* device.

NETBOOTING
----------
The initrd scripts have limited support for network booting.   This is
activated if the *ip*=<...> kernel parameter was given. Please refer to
the genkernel guide at 'https://wiki.gentoo.org/wiki/Genkernel' for more
information.

The initrd scripts will extract any *.tar.gz files found in the '/add'
directory of the livecd into the root filesystem during boot. This way
it is easy to extend a netbooted LiveCD i.e. add custom tools, or other
kernel modules.


REPORTING BUGS
--------------
If you believe you have found a bug in the genkernel scripts,  then
please file a bug on the Gentoo Linux Bugzilla against product
"Gentoo Hosted Projects" component "genkernel", i.e. at
'https://bugs.gentoo.org/enter_bug.cgi?product=Gentoo%20Hosted%20Projects&component=genkernel'.

If you're somewhat unsure if you hit a bug or not, file a bug an we'll find out together.
For general questions the is the gentoo-genkernel mailing list.  You can join the list
by sending empty mail to 'gentoo-genkernel+subscribe@lists.gentoo.org'.

We cannot assist you with kernel compilation failures unless they are
caused by a genkernel bug.

Kernel issues for Gentoo-supported kernels, including compilation failures
should go to 'https://bugs.gentoo.org/' and should be assigned to 'kernel@gentoo.org'.

Please check if an existing bug documents the same issue before opening
a new bug. Issues for kernel sources not supported by Gentoo should go
to their relevant authors.


AUTHORS
-------
- Tim Yamin <plasmaroo@gentoo.org>
- Eric Edgar <rocket@gentoo.org>
- Chris Gianelloni <wolf31o2@gentoo.org>
- Sebastian Pipping <sebastian@pipping.org>
- Robin H. Johnson <robbat2@gentoo.org>
- Thomas Deutschmann <whissi@gentoo.org>
- NFS Support by Thomas Seiler <thseiler@gmail.com>
- GnuPG 1.x integration by dacook <schism@subverted.org>
- MDADM integration by Matthias Dahl <ua_bugz_gentoo@mortal-soul.de>
- ZFS integration by Richard Yao <ryao@cs.stonybrook.edu>
- AUFS/Overlayfs by Zero_Chaos <zerochaos@gentoo.org> and likewhoa


SEE ALSO
--------
'/etc/initramfs.mounts' - additional required mounts before switching to real root

'/etc/genkernel.conf' - genkernel configuration file

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