HardenedBSD/stand/defaults/loader.conf.5

.\" Copyright (c) 1999 Daniel C. Sobral
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.Dd July 8, 2024
.Dt LOADER.CONF 5
.Os
.Sh NAME
.Nm loader.conf
.Nd "system bootstrap configuration information"
.Sh DESCRIPTION
The file
.Nm
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
.Xr loader 8 .
.Sh SYNTAX
Though
.Nm Ns 's
format was defined explicitly to resemble
.Xr rc.conf 5 ,
and can be sourced by
.Xr 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.
.Pp
The general parsing rules are:
.Bl -bullet
.It
Spaces and empty lines are ignored.
.It
A # sign will mark the remainder of the line as a comment.
.It
Only one setting can be present on each line.
.El
.Pp
All settings have the following format:
.Pp
.Dl variable="value"
.Pp
Unless it belongs to one of the classes of settings that receive special
treatment, a setting will set the value of a
.Xr loader 8
environment variable.
The settings that receive special
treatment are listed below.
Settings beginning with
.Qq *
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.
.Bl -tag -width Ar
.It Ar autoboot_delay
Delay in seconds before automatically booting.
A user with console access will be able to interrupt the
.Ic autoboot
process and escape into the interactive mode by pressing a key on
the console during this delay.
.Pp
If set to
.Dq Li NO ,
no
.Ic autoboot
is automatically attempted after processing
.Pa /boot/loader.rc ,
though explicit
.Ic autoboot Ns 's
are processed normally, using a 10 second delay.
.Pp
If set to
.Dq Li 0 ,
no delay is inserted, but any keys pressed while the kernel and modules are
loaded will enter interactive mode.
.Pp
If set to
.Dq Li -1 ,
no delay will be inserted and
.Nm
starts interactive mode only if
.Ic autoboot
has failed.
In combination with the
.Va beastie_disable
option, this option prevents users with console access from being able
to interrupt the
.Ic autoboot
process and escape to the loader prompt.
To use the
.Va autoboot_delay
option in this manner,
.Va beastie_disable
must be set to
.Dq Li YES .
.It Ar exec
Immediately executes a
.Xr loader 8
command.
This type of setting cannot be processed by programs other
than
.Xr loader 8 ,
so its use should be avoided.
Multiple instances of it will be processed
independently.
.It Ar loader_conf_dirs
Space separated list of directories to process for configuration files.
The lua-based loader will process files with a
.Dq .conf
suffix that are placed in these directories.
Files found here are processed after the ones listed in
.Va loader_conf_files
but before the ones found in
.Va local_loader_conf_files .
.It Ar loader_conf_files
Defines additional configuration files to be processed right after the
present file.
.Ar 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.
.It Ar local_loader_conf_files
Space separated list of additional configuration files to be processed at last,
i.e., after
.Va loader_conf_files
and
.Va loader_conf_dirs
are processed.
.It Ar product_vars
When set, must be a space separated list of environment variable names to walk
through to guess product information.
The order matters as reading a config file override the previously defined
values.
Undefined variables are silently ignored.
.Pp
When product information can be guessed, for each product information found,
append
.Pa /boot/loader.conf.d/PRODUCT
to
.Ar loader_conf_dirs .
It can be typically used as follow:
.Bd -literal
smbios.system.planar.maker="PLANAR_MAKER"
smbios.system.planar.product="PLANAR_PRODUCT"
smbios.system.product="PRODUCT"
uboot.m_product="M_PRODUCT"
product_vars="smbios.system.planar.maker smbios.system.planar.product smbios.system.product uboot.m_product"
.Ed
.Pp
to read files found in the following directories, in that order:
.Bl -bullet -compact
.It
.Pa /boot/loader.conf.d/PLANAR_MAKER
.It
.Pa /boot/loader.conf.d/PLANAR_PRODUCT
.It
.Pa /boot/loader.conf.d/PRODUCT
.It
.Pa /boot/loader.conf.d/M_PRODUCT
.El
.It Ar 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
.Pa /boot
that contains a kernel.
.It Ar kernel_options
Flags to be passed to the kernel.
.It Ar vfs.root.mountfrom
Specify the root partition to mount.
For example:
.Pp
.Dl vfs.root.mountfrom="ufs:/dev/da0s1a"
.Pp
.Xr loader 8
automatically calculates the value of this tunable from
.Pa /etc/fstab
from the partition the kernel was loaded from.
The calculated value might be calculated incorrectly when
.Pa /etc/fstab
is not available during
.Xr 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
.Pa /loader.conf .
.Pp
The value can also be overridden from the
.Xr loader 8
command line.
This is useful for system recovery when
.Pa /etc/fstab
is damaged, lost, or read from the wrong partition.
.It Ar password
Protect boot menu with a password without interrupting
.Ic 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
.Va autoboot_delay
variable or
.Ic autoboot
process fails.
In both cases user should provide specified password to be able to access boot
menu.
.It Ar 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.
.It Ar verbose_loading
If set to
.Dq YES ,
module names will be displayed as they are loaded.
.It Ar module_blacklist
Blacklist of modules.
Modules specified in the blacklist may not be loaded automatically with a
.Ar *_load
directive, but they may be loaded directly at the
.Xr loader 8
prompt.
Blacklisted modules may still be loaded indirectly as dependencies of other
modules.
.It Ar *_load
If set to
.Dq 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.
.It Ar *_name
Defines the name of the module.
.It Ar *_type
Defines the module's type.
If none is given, it defaults to a kld module.
.It Ar *_flags
Flags and parameters to be passed to the module.
.It Ar *_before
Commands to be executed before the module is loaded.
Use of this setting
should be avoided.
.It Ar *_after
Commands to be executed after the module is loaded.
Use of this setting
should be avoided.
.It Ar *_error
Commands to be executed if the loading of a module fails.
Except for the
special value
.Dq abort ,
which aborts the bootstrap process, use of this setting should be avoided.
.El
.Pp
.Em WARNING :
developers should never use these suffixes for any kernel environment
variables (tunables) or conflicts will result.
.Sh DEFAULT SETTINGS
Most of
.Nm Ns 's
default settings can be ignored.
The few of them which are important
or useful are:
.Bl -tag -width bootfile -offset indent
.It Va local_loader_conf_files
.Pq Dq /boot/loader.conf.local
Ensure
.Va loader.conf.local
can always be used to override settings from files found in
.Va loader_conf_files
and
.Va loader_conf_dirs .
.It Va bitmap_load
.Pq Dq NO
If set to
.Dq YES ,
a bitmap will be loaded to be displayed on screen while booting.
.It Va bitmap_name
.Pq Dq Pa /boot/splash.bmp
Name of the bitmap to be loaded.
Any other name can be used.
.It Va comconsole_speed
.Dq ( 115200
or the value of the
.Va BOOT_COMCONSOLE_SPEED
variable when
.Xr 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.
.It Va console
.Pq Dq vidconsole
.Dq comconsole
selects serial console,
.Dq vidconsole
selects the video console,
.Dq efi
selects the EFI console,
.Dq nullconsole
selects a mute console
(useful for systems with neither a video console nor a serial port), and
.Dq spinconsole
selects the video console which prevents any input and hides all output
replacing it with
.Dq spinning
character (useful for embedded products and such).
.It Va screen.font
Set font size for framebuffer mode.
The default font size is selected based on screen resolution.
Note that the terminal's size may vary.
.It Va screen.textmode
Value
.Dq 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
.Va vbe_max_resolution .
.Pp
Value
.Dq 1
will force BIOS loader to use VGA text mode.
.Pp
If
.Va vbe_max_resolution
is not set, the loader will try to set screen resolution based on EDID
information.
If EDID is not available, the default resolution is 800x600 (if available).
.It Va screen.height
.It Va screen.width
.It Va screen.depth
.Va screen.height ,
.Va screen.width ,
.Va screen.depth
are set by loader when loader is using framebuffer mode to draw the screen.
.It Va efi_max_resolution
.It Va vbe_max_resolution
Specify the maximum desired resolution for the EFI or VBE framebuffer console.
The following values are accepted:
.Bl -column "WidthxHeight"
.It Sy Value Ta Sy Resolution
.It 480p Ta 640x480
.It 720p Ta 1280x720
.It 1080p Ta 1920x1080
.It 1440p Ta 2560x1440
.It 2160p Ta 3840x2160
.It 4k Ta 3840x2160
.It 5k Ta 5120x2880
.It Va Width Ns x Ns Va Height Ta Va Width Ns x Ns Va Height
.El
.It Va kernel
.Pq Dq kernel
.It Va kernels
.Pq Dq kernel kernel.old
Space or comma separated list of kernels to present in the boot menu.
.It Va loader_conf_files
.Pq Dq Pa /boot/loader.conf /boot/loader.conf.local
.It Va loader_conf_dirs
.Pq Dq Pa /boot/loader.conf.d
.It Va splash_bmp_load
.Pq Dq NO
If set to
.Dq YES ,
will load the splash screen module, making it possible to display a bmp image
on the screen while booting.
.It Va splash_pcx_load
.Pq Dq NO
If set to
.Dq YES ,
will load the splash screen module, making it possible to display a pcx image
on the screen while booting.
.It Va vesa_load
.Pq Dq NO
If set to
.Dq YES ,
the vesa module will be loaded, enabling bitmaps above VGA resolution to
be displayed.
.It Va beastie_disable
If set to
.Dq YES ,
the beastie boot menu will be skipped.
.It Va loader_logo Pq Dq Li orbbw
Selects a desired logo in the beastie boot menu.
Possible values are:
.Dq Li orbbw ,
.Dq Li orb ,
.Dq Li fbsdbw ,
.Dq Li beastiebw ,
.Dq Li beastie ,
and
.Dq Li none .
.It Va loader_color
If set to
.Dq NO ,
the beastie boot menu will be displayed without ANSI coloring.
.It Va entropy_cache_load
.Pq Dq YES
If set to
.Dq NO ,
the very early
boot-time entropy file
will not be loaded.
See the entropy entries in
.Xr rc.conf 5 .
.It Va entropy_cache_name
.Pq Dq /boot/entropy
The name of the very early
boot-time entropy cache file.
.It Va cpu_microcode_load
.Pq Dq NO
If set to
.Dq YES ,
the microcode update file specified by
.Va cpu_microcode_name
will be loaded and applied very early during boot.
This provides functionality similar to
.Xr 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
.Dv i386
and
.Dv amd64
processors.
It has no effect on other processor types.
.It Va cpu_microcode_name
A path to a microcode update file.
.El
.Sh OTHER SETTINGS
Other settings that may be used in
.Nm
that have no default value:
.Bl -tag -width bootfile -offset indent
.It Va fdt_overlays
Specifies a comma-delimited list of FDT overlays to apply.
.Pa /boot/dtb/overlays
is created by default for overlays to be placed in.
.It Va kernels_autodetect
If set to
.Dq YES ,
attempt to auto-detect kernels installed in
.Pa /boot .
This is an option specific to the Lua-based loader.
It is not available in the default Forth-based loader.
.El
.Sh FILES
.Bl -tag -width /boot/defaults/loader.conf -compact
.It Pa /boot/defaults/loader.conf
Default settings \(em do not change this file.
.It Pa /boot/loader.conf
User defined settings.
.It Pa /boot/loader.conf.lua
User defined settings written in lua.
.It Pa /boot/loader.conf.d/*.conf
User defined settings split in separate files.
.It Pa /boot/loader.conf.d/*.lua
User defined settings written in lua and split in separate files.
.It Pa /boot/loader.conf.local
Machine-specific settings for sites with a common loader.conf. Allow to override
settings defined in other files.
.El
.Sh SEE ALSO
.Xr kenv 1 ,
.Xr loader.conf.lua 5 ,
.Xr rc.conf 5 ,
.Xr boot 8 ,
.Xr cpucontrol 8 ,
.Xr loader 8 ,
.Xr loader.4th 8
.Sh HISTORY
The file
.Nm
first appeared in
.Fx 3.2 .
.Sh AUTHORS
This manual page was written by
.An Daniel C. Sobral Aq dcs@FreeBSD.org .
.Sh BUGS
The
.Xr loader 8
stops reading
.Nm
when it encounters a syntax error, so any options which are vital for
booting a particular system (i.e.,
.Dq Va hw.ata.ata_dma Ns "=0" )
should precede any experimental additions to
.Nm .