loader.conf —
system bootstrap configuration information
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).
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:
- Spaces and empty lines are ignored.
- A # sign will mark the remainder of the line as a comment.
- 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”.
- exec
- Immediately executes a
loader(8) command. This
type of setting cannot be processed by programs other than
loader(8), so its use
should be avoided. Multiple instances of it will be processed
independently.
- loader_conf_dirs
- Space separated list of directories to process for 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.
- *_load
- If set to “YES”, that module will be loaded. If no name is
defined (see below), the module's name is taken to be the same as the
prefix.
- *_name
- Defines the name of the module.
- *_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.
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
- (“9600” 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).
- efi_max_resolution
- Specify the maximum desired resolution for the EFI 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.
- entropy_cache_load
- (“YES”) If set to “NO”, the very early
boot-time entropy file will not be loaded. See the entropy entries in
rc.conf(5).
- entropy_cache_name
- (“/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 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.
- /boot/defaults/loader.conf
- default settings -- do not change this file.
- /boot/loader.conf
- user defined settings.
- /boot/loader.conf.local
- machine-specific settings for sites with a common loader.conf.
The file loader.conf first appeared in
FreeBSD 3.2.
This manual page was written by Daniel C.
Sobral ⟨dcs@FreeBSD.org⟩.
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.