initramfs.conf(5) [linux man page]
INITRAMFS.CONF(5) initramfs.conf manual INITRAMFS.CONF(5) NAME
initramfs.conf - configuration file for mkinitramfs DESCRIPTION
The behaviour of mkinitramfs can be modified by its configuration file. Each line in the file can be a configuration variable, a blank line, or a comment. The value of an variable is assigned by an statement of the form: name=[value] Configuration options can be broken out into configuration snippets and placed in individual files in the /etc/mkinitramfs/conf.d direc- tory. Files in this directory are always read after the main configuration file, so you can override the settings in the main config file without editing it directly. GENERAL VARIABLES
MODULES Specifies the modules for the initramfs image. Modules listed in /etc/initramfs-tools/modules and /usr/share/initramfs-tools/modules.d/* are always included in the initramfs, and are loaded early in the boot process. list doesn't load any additional modules at boot time, other than those listed in the above files. most adds most file system, all ata, sata, scsi and usb drivers. dep tries to guess which modules are necessary for the running box and only adds those modules. netboot adds the base and network modules, but skips block devices. The default setting is most. BUSYBOX Include busybox utilities for the boot scripts. If set to 'n' mkinitramfs will build an initramfs without busybox. Beware that many boot scripts need busybox utilities. COMPRESS Specifies the compression method used for the initramfs image. mkinitramfs will default to gzip if the kernel lacks support (CON- FIG_RD) or the corresponding userspace utility is not present. UMASK Set the umask value of the generated initramfs file. Useful to not disclose eventual keys. COMPCACHE_SIZE Amount of RAM to use for RAM-based compressed swap space. The default is not to use compcache. An empty value - compcache isn't used, or added to the initramfs at all. An integer and K (e.g. 65536 K) - use a number of kilobytes. An integer and M (e.g. 256 M) - use a number of megabytes. An integer and G (e.g. 1 G) - use a number of gigabytes. An integer and % (e.g. 50 %) - use a percentage of the amount of RAM. You can optionally install the compcache package to configure this setting via debconf and have userspace scripts to load and unload compcache. NFS VARIABLES
BOOT Allows one to use an nfs drive as the root of the drive. The default is to boot from local media (hard drive, USB stick). Set to nfs for an NFS root share. DEVICE Specifies the network interface, like eth0. ROOT Allows optional root bootarg hardcoding, when no root bootarg can be passed. A root bootarg overrides that special setting. NFSROOT Defaults to auto in order to pick up value from DHCP server. Otherwise you need to specify HOST:MOUNT. FILES
/etc/initramfs-tools/initramfs.conf AUTHOR
The initramfs-tools are written by Maximilian Attems <maks@debian.org>, Jeff Bailey <jbailey@raspberryginger.com> and numerous others. Loosely based on mkinitrd.conf by Herbert Xu. SEE ALSO
initramfs-tools(8), mkinitramfs(8), update-initramfs(8). Linux 2010/11/22 INITRAMFS.CONF(5)
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MKINITRAMFS(8) mkinitramfs manual MKINITRAMFS(8) NAME
mkinitramfs - low-level tool for generating an initramfs image SYNOPSIS
mkinitramfs [-c compress] [-d confdir] [-k] -o outfile [-r root] [-v] [version] mkinitramfs [--supported-host-version= hversion] mkinitramfs [--supported-target-version= tversion] DESCRIPTION
The mkinitramfs script generates an initramfs image. The initramfs is a compressed cpio archive. The archive can be used on a different box of the same arch with the corresponding Linux kernel. mkinitramfs is meant for advanced usage. On your local box update-initramfs calls mkinitramfs with the relevant parameters. update-initramfs keeps sha1sum of generated initramfs. It takes care to generate backups and eventually runs the bootloader. At boot time, the kernel unpacks that archive into RAM disk, mounts and uses it as initial root file system. All finding of the root device happens in this early userspace. OPTIONS
-c compress Override the COMPRESS setting in initramfs.conf. -d confdir Set an alternate configuration directory. -k Keep the temporary directory used to make the image. -o outfile Write the image to outfile. -r root Override the ROOT setting in initramfs.conf. -v Set the verbose mode output. version Set the kernel version of the initramfs image (defaults to the running kernel). --supported-host-version=hversion This option queries if mkinitramfs can create ramdisks on a running kernel of version hversion. --supported-target-version=tversion This option queries if mkinitramfs can create ramdisks for kernel version tversion. ENVIRONMENT
mkinitramfs honours the TMPDIR environment variable. If set, it uses subdirectories in the given directory to create its temporary working directories. Else it uses /tmp as default value for that purpose. The given directory should be on a filesystem which allows the execution of files stored there, i.e. should not be mounted with the noexec mount option. FILES
/etc/initramfs-tools/initramfs.conf The default configuration file for the script. See initramfs.conf(5) for a description of the available configuration parameter. /etc/initramfs-tools/modules Specified modules will be put in the generated image and loaded when the system boots. The format - one per line - is identical to that of /etc/modules, which is described in modules(5). /etc/initramfs-tools/conf.d The conf.d directory allows one to hardcode bootargs at initramfs build time via config snippets. This allows one to set ROOT or RESUME. This is especially useful for bootloaders, which do not pass an root bootarg. /etc/initramfs-tools/DSDT.aml If this file exists, it will be appended to the initramfs in a way that causes it to be loaded by ACPI. EXAMPLES
Create an initramfs for current running kernel: mkinitramfs -o ~/tmp/initramfs-$(uname -r) Create an initramfs for specific kernel and keep builddirs: mkinitramfs -k -o ~/tmp/initramfs-2.6.21-686 2.6.21-686 Debug initramfs creation (check out written logfile) sh -x mkinitramfs -o ~/tmp/initramfs-$(uname -r) 2> ~/tmp/log AUTHOR
The initramfs-tools are written by Maximilian Attems <maks@debian.org>, Jeff Bailey <jbailey@raspberryginger.com> and numerous others. SEE ALSO
initramfs.conf(5), initramfs-tools(8), update-initramfs(8). Linux 2010/04/07 MKINITRAMFS(8)