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download PDF document: loader.conf.5.pdf

LOADER.CONF(5) FreeBSD File Formats Manual LOADER.CONF(5)
NAME loader.conf - system bootstrap configuration information
DESCRIPTION The file loader.conf contains descriptive information on bootstrapping the system. Through it you can specify the kernel to be booted, parameters to be passed to it, and additional modules to be loaded; and generally set all variables described in loader(8).
SYNTAX Though loader.conf's format was defined explicitly to resemble rc.conf(5), and can be sourced by sh(1), some settings are treated in a special fashion. Also, the behavior of some settings is defined by the setting's suffix; the prefix identifies which module the setting controls.
The general parsing rules are:
o Spaces and empty lines are ignored.
o A # sign will mark the remainder of the line as a comment.
o Only one setting can be present on each line.
All settings have the following format:
variable="value"
Unless it belongs to one of the classes of settings that receive special treatment, a setting will set the value of a loader(8) environment variable. The settings that receive special treatment are listed below. Settings beginning with "*" below define the modules to be loaded and may have any prefix; the prefix identifies a module. All such settings sharing a common prefix refer to the same module.
autoboot_delay Delay in seconds before automatically booting. A user with console access will be able to interrupt the autoboot process and escape into the interactive mode by pressing a key on the console during this delay.
If set to "NO", no autoboot is automatically attempted after processing /boot/loader.rc, though explicit autoboot's are processed normally, using a 10 second delay.
If set to "0", no delay is inserted, but any keys pressed while the kernel and modules are loaded will enter interactive mode.
If set to "-1", no delay will be inserted and loader.conf starts interactive mode only if autoboot has failed. In combination with the beastie_disable option, this option prevents users with console access from being able to interrupt the autoboot process and escape to the loader prompt. To use the autoboot_delay option in this manner, beastie_disable must be set to "YES".
configuration files. The lua-based loader will process files with a ".conf" suffix that are placed in these directories.
loader_conf_files Defines additional configuration files to be processed right after the present file. loader_conf_files should be treated as write-only. One cannot depend on any value remaining in the loader environment or carried over into the kernel environment.
kernel Name of the kernel to be loaded. If no kernel name is set, no additional modules will be loaded. The name must be a subdirectory of /boot that contains a kernel.
kernel_options Flags to be passed to the kernel.
vfs.root.mountfrom Specify the root partition to mount. For example:
vfs.root.mountfrom="ufs:/dev/da0s1a"
loader(8) automatically calculates the value of this tunable from /etc/fstab from the partition the kernel was loaded from. The calculated value might be calculated incorrectly when /etc/fstab is not available during loader(8) startup (as during diskless booting from NFS), or if a different device is desired by the user. The preferred value can be set in /loader.conf.
The value can also be overridden from the loader(8) command line. This is useful for system recovery when /etc/fstab is damaged, lost, or read from the wrong partition.
password Protect boot menu with a password without interrupting autoboot process. The password should be in clear text format. If a password is set, boot menu will not appear until any key is pressed during countdown period specified by autoboot_delay variable or autoboot process fails. In both cases user should provide specified password to be able to access boot menu.
bootlock_password Provides a password to be required by check-password before execution is allowed to continue. The password should be in clear text format. If a password is set, the user must provide specified password to boot.
verbose_loading If set to "YES", module names will be displayed as they are loaded.
module_blacklist Blacklist of modules. Modules specified in the blacklist may not be loaded automatically with a *_load directive, but they may be loaded directly at the loader(8) prompt. Blacklisted modules may still be loaded indirectly as dependencies of other modules.
*_type Defines the module's type. If none is given, it defaults to a kld module.
*_flags Flags and parameters to be passed to the module.
*_before Commands to be executed before the module is loaded. Use of this setting should be avoided.
*_after Commands to be executed after the module is loaded. Use of this setting should be avoided.
*_error Commands to be executed if the loading of a module fails. Except for the special value "abort", which aborts the bootstrap process, use of this setting should be avoided.
WARNING: developers should never use these suffixes for any kernel environment variables (tunables) or conflicts will result.
DEFAULT SETTINGS Most of loader.conf's default settings can be ignored. The few of them which are important or useful are:
bitmap_load ("NO") If set to "YES", a bitmap will be loaded to be displayed on screen while booting.
bitmap_name ("/boot/splash.bmp") Name of the bitmap to be loaded. Any other name can be used.
comconsole_speed ("115200" or the value of the BOOT_COMCONSOLE_SPEED variable when loader(8) was compiled). Sets the speed of the serial console. If the previous boot loader stage specified that a serial console is in use then the default speed is determined from the current serial port speed setting.
console ("vidconsole") "comconsole" selects serial console, "vidconsole" selects the video console, "efi" selects the EFI console, "nullconsole" selects a mute console (useful for systems with neither a video console nor a serial port), and "spinconsole" selects the video console which prevents any input and hides all output replacing it with "spinning" character (useful for embedded products and such).
screen.font Set font size for framebuffer mode. Default font size is selected based on screen resolution, to achieve terminal dimensions 80x24.
screen.textmode Value "0" will trigger BIOS loader to switch to use VESA BIOS Extension (VBE) frame buffer mode for console. The same effect can be achieved by setting vbe_max_resolution.
Value "1" will force BIOS loader to use VGA text mode.
screen.width
screen.depth screen.height, screen.width, screen.depth are set by loader when loader is using framebuffer mode to draw the screen.
efi_max_resolution
vbe_max_resolution Specify the maximum desired resolution for the EFI or VBE framebuffer console. The following values are accepted:
Value Resolution 480p 640x480 720p 1280x720 1080p 1920x1080 2160p 3840x2160 4k 3840x2160 5k 5120x2880 WidthxHeight WidthxHeight
kernel ("kernel")
kernels ("kernel kernel.old") Space or comma separated list of kernels to present in the boot menu.
loader_conf_files ("/boot/loader.conf /boot/loader.conf.local")
loader_conf_dirs ("/boot/loader.conf.d")
splash_bmp_load ("NO") If set to "YES", will load the splash screen module, making it possible to display a bmp image on the screen while booting.
splash_pcx_load ("NO") If set to "YES", will load the splash screen module, making it possible to display a pcx image on the screen while booting.
vesa_load ("NO") If set to "YES", the vesa module will be loaded, enabling bitmaps above VGA resolution to be displayed.
beastie_disable If set to "YES", the beastie boot menu will be skipped.
loader_logo ("orbbw") Selects a desired logo in the beastie boot menu. Possible values are: "orbbw", "orb", "fbsdbw", "beastiebw", "beastie", and "none".
loader_color If set to "NO", the beastie boot menu will be displayed without ANSI coloring. ("/boot/entropy") The name of the very early boot-time entropy cache file.
cpu_microcode_load ("NO") If set to "YES", the microcode update file specified by cpu_microcode_name will be loaded and applied very early during boot. This provides functionality similar to cpucontrol(8) but ensures that CPU features enabled by microcode updates can be used by the kernel. The update will be re-applied automatically when resuming from an ACPI sleep state. If the update file contains updates for multiple processor models, the kernel will search for and extract a matching update. Currently this setting is supported only on Intel i386 and amd64 processors. It has no effect on other processor types.
cpu_microcode_name A path to a microcode update file.
OTHER SETTINGS Other settings that may be used in loader.conf that have no default value:
fdt_overlays Specifies a comma-delimited list of FDT overlays to apply. /boot/dtb/overlays is created by default for overlays to be placed in.
kernels_autodetect If set to "YES", attempt to auto-detect kernels installed in /boot. This is an option specific to the Lua-based loader. It is not available in the default Forth-based loader.
FILES /boot/defaults/loader.conf default settings -- do not change this file. /boot/loader.conf user defined settings. /boot/loader.conf.lua user defined settings written in lua. /boot/loader.conf.local machine-specific settings for sites with a common loader.conf.
SEE ALSO loader.conf.lua(5), rc.conf(5), boot(8), cpucontrol(8), loader(8), loader.4th(8)
HISTORY The file loader.conf first appeared in FreeBSD 3.2.
AUTHORS This manual page was written by Daniel C. Sobral <dcs@FreeBSD.org>.
BUGS The loader(8) stops reading loader.conf when it encounters a syntax error, so any options which are vital for booting a particular system (i.e., "hw.ata.ata_dma=0") should precede any experimental additions to loader.conf.
FreeBSD 14.0-RELEASE-p11 July 31, 2021 FreeBSD 14.0-RELEASE-p11