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You are here: manpages

GENKERNEL

Section: genkernel 4&.3&.17 (8)
Updated: 09/22/2025
Index Return to Main Contents

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 genkernelcqs 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:

%%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 built, installed, --kernel-modules-prefix is not set.

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 isncqt a previous config. Use the special value default to force usage of default kernel config.

--kernel-modules-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-cross-compile=<target triplet>

: Target triple (i.e. aarch64-linux-gnu) to build kernel for.

--kernel-ar=<archiver>

: Archiver to use for the kernel compilation.

--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=<makeprog>

: GNU Make to use for the kernel compilation.

--kernel-nm=<nm>

: NM utility to use for the kernel compilation.

--kernel-objcopy=<objcopyprog>

: Objcopy utility to use for the kernel compilation.

--kernel-objdump=<objdumpprog>

: Objdump utility to use for the kernel compilation.

--kernel-ranlib=<ranlibprog>

: Ranlib utility to use for the kernel compilation.

--kernel-readelf=<readelfprog>

: Readelf utility to use for the kernel compilation.

--kernel-strip=<stripprog>

: Strip utility 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-ar=<archiver>

: Archiver to use for utilities.

--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.

--utils-nm=<nm>

: NM utility to use for utilities.

--utils-objcopy=<objcopyprog>

: Objcopy utility to use for utilities.

--utils-objdump=<objdumpprog>

: Objdump utility to use for utilities.

--utils-ranlib=<ranlibprog>

: Ranlib utility to use for utilities.

--utils-readelf=<readelfprof>

: Readelf utility to use for utilities.

--utils-strip=<striprog>

: Strip utility 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.

--[no-]plymouth

: Includes or excludes Plymouth from the initramfs. If "splash" is passed at boot, Plymouth will be activated.

--plymouth-theme=<theme>

: Embeds the given Plymouth theme into the initramfs.

--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-]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-]keyctl

: Includes or excludes support for keyutils keyctl. This way a LUKS passphrase can be loaded into a keyring at boot time to unlock multiple devices (root, swap, etc.) without retyping it for each one.

--[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 genkernelcqs 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:

%%ARCH%%	Will be replaced with genkernel arch value, for example x86_64.
%%KV%%	Will be replaced with kernel version, for example 5.2.-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.

--[no-]all-firmware

: Enable or disable copying of all firmware into initramfs

--firmware-dir=<dir>

: Specify directory to copy firmware from (defaults to /lib/firmware).

--firmware-files=<files>

: Specifies specific firmware files or directories to copy, relative to --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_root_options=<...>

: This specifies additional options, which should get passed to cryptsetup when opening root volume. Can be specified multiple times or separate multiple options with a comma.

crypt_swap=<...>

: This specifies the swap device encrypted by LUKS.

crypt_swap_options=<...>

: This specifies additional options, which should get passed to cryptsetup when opening swap volume. Can be specified multiple times or separate multiple options with a comma.

root_header=<...>

: In case your encrypted root uses a LUKS detached header, you can use a device like a usb pen to store the header file. This value should be the key path relative to the mount point.

root_headerdev=<...>

: If necessary provide the name of the device that carries the root_header. If unset while using root_header, it will automatically look for the device in every boot.

root_headerdev_fstype=<...>

: Used filesystem for root_headerdev. See rootfstype for more details.

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_keydev_fstype=<...>

: Used filesystem for root_keydev. See rootfstype for more details.

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_header=<...>

: Same as root_header for swap.

swap_headerdev=<...>

: Same as root_headerdev for swap.

swap_headerdev_fstype=<...>

: Used filesystem for swap_headerdev. See rootfstype for more details.

swap_key=<...>

: Same as root_key for swap.

swap_keydev=<...>

: Same as root_keydev for swap.

swap_keydev_fstype=<...>

: Used filesystem for swap_keydev. See rootfstype for more details.

keyctl_keydesc=<...>

: Load a passphrase into a keyring at boot time under the key name provided as an argument to this option. This way multiple devices (root, swap, etc.) can be unlocked without retyping the passphrase for each one. Youcqll need to add this key name as a keyring token to every LUKS device that it is supposed to unlock - have a look at cryptsetup token add operation.

keyctl_keykeep

: Doncqt remove the newly added key before starting the real init. Useful if you want to utilize it to unlock LUKS devices post-initramfs.

keyctl_keytimeout=<...>

: Enable a timeout (in seconds) for the newly added key. This option normally only makes sense when used together with the keyctl_keykeep option.

crypt_silent

: Set this to silent all the output related to the cryptographic software, and in case your encrypted device isncqt 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 IPv6cqs 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.debug=<...>

: This boolean option allows you to run udevd in debug mode. Output will be logged to /run/initramfs/udevd.log.

gk.udev.timeout=<...>

: By default we will wait up to 120 seconds (UDEV default) for UDEV event queue to become empty.

gk.preserverun.disabled=<...>

: By default, switch_root will preserve and move already mounted /run to newroot. This boolean option allows you to disable preserving of /run, which is maybe required for SELinux due to missing labeling support in genkernel.

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.

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.

domultipath

: Activate Multipath on bootup.

doscsi

: Activate SCSI devices on bootup, necessary when SCSI support is compiled as modules and youcqre 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 or used filesystem was not built into kernel. 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.emergency=<reboot|poweroff|halt>

: By default, genkernel tries to spawn a rescue shell in case of a critical failure (see gk.userinteraction.disabled to prevent this). This option controls the action to execute when rescue is not possible. Default is "halt".

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.hw.use-modules_load=<...>

: By default, genkernel relies on UDEVcqs capability to load required kernel modules. This boolean option allows you to force old module loading depending on modules_load file until root device becomes available.

gk.log.disabled=<...>

: By default, any shown message and external command calls will be logged to /run/initramfs/init.log. This boolean option allows you to disable logging for some reason.

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, on error, system will immediately execute gk.emergency action.

noload=<...>

: List of modules to skip loading. Separate using commas or spaces.

Note

This option has only an effect when gk.hw.use-modules_load is enabled.

doload=<...>

: List of modules which should always be loaded.

domodules, nomodules

: Enables/disables loading of modules in general.

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, genkernelcqs 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 youcqre somewhat unsure if you hit a bug or not, file a bug an wecqll 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.