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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"

"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">

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<refentry id="loader.conf" conditional='ENABLE_BOOTLOADER'

xmlns:xi="http://www.w3.org/2001/XInclude">

<refentryinfo>

<title>loader.conf</title>

<productname>systemd</productname>

</refentryinfo>

<refmeta>

<refentrytitle>loader.conf</refentrytitle>

<manvolnum>5</manvolnum>

</refmeta>

<refnamediv>

<refname>loader.conf</refname>

<refpurpose>Configuration file for systemd-boot</refpurpose>

</refnamediv>

<refsynopsisdiv>

<para><filename><replaceable>ESP</replaceable>/loader/loader.conf</filename>,

<filename><replaceable>ESP</replaceable>/loader/entries/*.conf</filename>

<filename><replaceable>XBOOTLDR</replaceable>/loader/entries/*.conf</filename>

</para>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para>

<citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry> will

read <filename><replaceable>ESP</replaceable>/loader/loader.conf</filename>, and any files with the

<literal>.conf</literal> extension under

<filename><replaceable>ESP</replaceable>/loader/entries/</filename> on the EFI system partition (ESP),

and <filename><replaceable>XBOOTLDR</replaceable>/loader/entries/</filename> on the extended boot loader

partition (XBOOTLDR) as defined by <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader

Specification</ulink>.

</para>

<para>Each of these configuration files must consist of series of newline (i.e. ASCII code 10) separated

lines, each consisting of an option name, followed by whitespace, and the option

value. <literal>#</literal> may be used to start a comment line. Empty and comment lines are ignored. The

files use UTF-8 encoding.</para>

<para>Boolean arguments may be written as

<literal>yes</literal>/<literal>y</literal>/<literal>true</literal>/<literal>t</literal>/<literal>on</literal>/<literal>1</literal> or

<literal>no</literal>/<literal>n</literal>/<literal>false</literal>/<literal>f</literal>/<literal>off</literal>/<literal>0</literal>.

</para>

</refsect1>

<refsect1>

<title>Options</title>

<para>The configuration options supported by

<filename><replaceable>ESP</replaceable>/loader/entries/*.conf</filename> and

<filename><replaceable>XBOOTLDR</replaceable>/loader/entries/*.conf</filename> files are defined as part

of the <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader

Specification</ulink>.</para>

<para>The following configuration are supported by the <filename>loader.conf</filename> configuration

file:</para>

<variablelist>

<varlistentry>

<term>default</term>

<listitem><para>A glob pattern to select the default entry. The default entry

may be changed in the boot menu itself, in which case the name of the

selected entry will be stored as an EFI variable, overriding this option.

</para>

<para>If set to <literal>@saved</literal> the chosen entry will be saved as an EFI variable

on every boot and automatically selected the next time the boot loader starts.</para>

<table>

<title>Automatically detected entries will use the following names:</title>

<tgroup cols='2'>

<colspec colname='name' />

<colspec colname='expl' />

<thead>

<row>

<entry>Name</entry>

<entry>Description</entry>

</row>

</thead>

<tbody>

<row>

<entry>auto-efi-default</entry>

<entry>EFI Default Loader</entry>

</row>

<row>

<entry>auto-efi-shell</entry>

<entry>EFI Shell</entry>

</row>

<row>

<entry>auto-osx</entry>

<entry>macOS</entry>

</row>

<row>

<entry>auto-poweroff</entry>

<entry>Power Off The System</entry>

</row>

<row>

<entry>auto-reboot</entry>

<entry>Reboot The System</entry>

</row>

<row>

<entry>auto-reboot-to-firmware-setup</entry>

<entry>Reboot Into Firmware Interface</entry>

</row>

<row>

<entry>auto-windows</entry>

<entry>Windows Boot Manager</entry>

</row>

</tbody>

</tgroup>

</table>

<para>Supported glob wildcard patterns are <literal>?</literal>, <literal>*</literal>, and

<literal>[…]</literal> (including ranges). Note that these patterns use the same syntax as

<citerefentry project='man-pages'><refentrytitle>glob</refentrytitle><manvolnum>7</manvolnum></citerefentry>,

but do not support all features. In particular, set negation and named character classes are not

supported. The matching is done case-insensitively on the entry ID (as shown by <command>bootctl

list</command>).</para>

<xi:include href="version-info.xml" xpointer="v239"/></listitem>

</varlistentry>

<varlistentry>

<term>timeout</term>

<listitem><para>How long the boot menu should be shown before the default

entry is booted, in seconds. This may be changed in the boot menu itself and

will be stored as an EFI variable in that case, overriding this option.

</para>

<para>If set to <literal>menu-disabled</literal> or <literal>menu-hidden</literal> or <literal>0</literal>

(the default), no menu is shown and the default entry will be booted immediately. Unless

<literal>menu-disabled</literal> is used, the menu can be shown

by pressing and holding a key before systemd-boot is launched. Setting this to

<literal>menu-force</literal> disables the timeout while always showing the menu.</para>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

<varlistentry>

<term>console-mode</term>

<listitem><para>This option configures the resolution of the console. This may be changed in

the boot menu itself and will be stored as an EFI variable in that case, overriding this

option.</para>

<para>Takes a number or one of the special values listed below. The following

values may be used:</para>

<variablelist>

<varlistentry>

<term>0</term>

<listitem>

<para>Standard UEFI 80x25 mode</para>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

<varlistentry>

<term>1</term>

<listitem>

<para>80x50 mode, not supported by all devices</para>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

<varlistentry>

<term>2</term>

<listitem>

<para>the first non-standard mode provided by the device

firmware, if any</para>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

<varlistentry>

<term>auto</term>

<listitem>

<para>Pick a suitable mode automatically using heuristics</para>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

<varlistentry>

<term>max</term>

<listitem>

<para>Pick the highest-numbered available mode</para>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

<varlistentry>

<term>keep</term>

<listitem>

<para>Keep the mode selected by firmware (the default)</para>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

</variablelist>

<xi:include href="version-info.xml" xpointer="v239"/>

</listitem>

</varlistentry>

<varlistentry>

<term>editor</term>

<listitem><para>Takes a boolean argument. Enable (the default) or disable the

editor. The editor should be disabled if the machine can be accessed by

unauthorized persons.</para>

<xi:include href="version-info.xml" xpointer="v239"/></listitem>

</varlistentry>

<varlistentry>

<term>auto-entries</term>

<listitem><para>Takes a boolean argument. Enable (the default) or disable

entries for other boot entries found on the boot partition. In particular,

this may be useful when loader entries are created to show replacement

descriptions for those entries.</para>

<xi:include href="version-info.xml" xpointer="v239"/></listitem>

</varlistentry>

<varlistentry>

<term>auto-firmware</term>

<listitem><para>A boolean controlling the presence of the <literal>Reboot Into Firmware

Interface</literal> entry (enabled by default). If this is disabled, the firmware interface may still

be reached by using the <keycap>f</keycap> key.</para>

<xi:include href="version-info.xml" xpointer="v239"/></listitem>

</varlistentry>

<varlistentry>

<term>beep</term>

<listitem><para>Takes a boolean argument. If timeout enabled beep every second, otherwise beep n times when n-th entry in boot menu is selected (default disabled).

Currently, only x86 is supported, where it uses the PC speaker.</para>

<xi:include href="version-info.xml" xpointer="v251"/></listitem>

</varlistentry>

<varlistentry>

<term>secure-boot-enroll</term>

<listitem><para>Danger: this feature might soft-brick your device if used improperly.</para>

<para>Controls enrollment of secure boot keys found on the ESP if the system is in setup mode:

<variablelist>

<varlistentry>

<term><option>off</option></term>

<listitem><para>No action is taken.</para>

<xi:include href="version-info.xml" xpointer="v253"/></listitem>

</varlistentry>

<varlistentry>

<term><option>manual</option></term>

<listitem><para>Boot entries for found secure boot keys are created that allow manual

enrollment.</para>

<xi:include href="version-info.xml" xpointer="v253"/></listitem>

</varlistentry>

<varlistentry>

<term><option>if-safe</option></term>

<listitem><para>Same behavior as <option>manual</option>, but will try to automatically

enroll the key <literal>auto</literal> if it is considered to be safe. Currently, this is only

the case if the system is running inside a virtual machine.</para>

<xi:include href="version-info.xml" xpointer="v253"/></listitem>

</varlistentry>

<varlistentry>

<term><option>force</option></term>

<listitem><para>Always enroll the <literal>auto</literal> key if found. Note that a warning

message with a timeout will still be shown if this operation is unknown to be safe.</para>

<xi:include href="version-info.xml" xpointer="v253"/></listitem>

</varlistentry>

</variablelist>

</para>

<para>The different sets of variables can be set up under

<filename>/loader/keys/<replaceable>NAME</replaceable></filename> where

<replaceable>NAME</replaceable> is the name that is going to be used as the name of the entry. This

allows one to ship multiple sets of Secure Boot variables and choose which one to enroll at runtime.

</para>

<para>Supported Secure Boot variables are one database for authorized images, one for the key

exchange key (KEK) and one for the platform key (PK). For more information, refer to the

<ulink url="https://uefi.org/specifications">UEFI specification</ulink>, under Secure Boot and Driver

Signing. Another resource that describe the interplay of the different variables is the

<ulink url="https://edk2-docs.gitbook.io/understanding-the-uefi-secure-boot-chain/secure_boot_chain_in_uefi/uefi_secure_boot">

EDK2 documentation</ulink>.</para>

<para>A complete set of UEFI variable includes <filename>db.auth</filename>, <filename>KEK.auth</filename>

and <filename>PK.auth</filename>. Note that these files need to be authenticated UEFI variables. See

below for an example of how to generate them from regular X.509 keys.</para>

<programlisting>uuid=$(systemd-id128 new --uuid)

for key in PK KEK db; do

openssl req -new -x509 -subj "/CN=${key}/" -keyout "${key}.key" -out "${key}.pem"

openssl x509 -outform DER -in "${key}.pem" -out "${key}.der"

sbsiglist --owner "${uuid}" --type x509 --output "${key}.esl" "${key}.der"

done

# See also: <ulink url="https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-secure-boot-key-creation-and-management-guidance">Windows Secure Boot Key Creation and Management Guidance</ulink>

curl --location \

"https://go.microsoft.com/fwlink/p/?linkid=321192" -o ms-db-2011.der \

"https://go.microsoft.com/fwlink/p/?linkid=321185" -o ms-kek-2011.der \

"https://go.microsoft.com/fwlink/p/?linkid=321194" -o ms-uefi-db-2011.der \

"https://go.microsoft.com/fwlink/p/?linkid=2239776" -o ms-db-2023.der \

"https://go.microsoft.com/fwlink/p/?linkid=2239775" -o ms-kek-2023.der \

"https://go.microsoft.com/fwlink/p/?linkid=2239872" -o ms-uefi-db-2023.der

sha1sum -c &lt;&lt;END

580a6f4cc4e4b669b9ebdc1b2b3e087b80d0678d ms-db-2011.der

31590bfd89c9d74ed087dfac66334b3931254b30 ms-kek-2011.der

46def63b5ce61cf8ba0de2e6639c1019d0ed14f3 ms-uefi-db-2011.der

45a0fa32604773c82433c3b7d59e7466b3ac0c67 ms-db-2023.der

459ab6fb5e284d272d5e3e6abc8ed663829d632b ms-kek-2023.der

b5eeb4a6706048073f0ed296e7f580a790b59eaa ms-uefi-db-2023.der

END

for key in ms-*.der; do

sbsiglist --owner 77fa9abd-0359-4d32-bd60-28f4e78f784b --type x509 --output "${key%der}esl" "${key}"

done

# Optionally add Microsoft Windows certificates (needed to boot into Windows).

cat ms-db-*.esl >>db.esl

# Optionally add Microsoft UEFI certificates for firmware drivers / option ROMs and third-party

# boot loaders (including shim). This is highly recommended on real hardware as not including this

# may soft-brick your device (see next paragraph).

cat ms-uefi-*.esl >>db.esl

# Optionally add Microsoft KEK certificates. Recommended if either of the Microsoft keys is used as

# the official UEFI revocation database is signed with this key. The revocation database can be

# updated with <citerefentry project='man-pages'><refentrytitle>fwupdmgr</refentrytitle><manvolnum>1</manvolnum></citerefentry>.

cat ms-kek-*.esl >>KEK.esl

attr=NON_VOLATILE,RUNTIME_ACCESS,BOOTSERVICE_ACCESS,TIME_BASED_AUTHENTICATED_WRITE_ACCESS

sbvarsign --attr "${attr}" --key PK.key --cert PK.pem --output PK.auth PK PK.esl

sbvarsign --attr "${attr}" --key PK.key --cert PK.pem --output KEK.auth KEK KEK.esl

sbvarsign --attr "${attr}" --key KEK.key --cert KEK.pem --output db.auth db db.esl

</programlisting>

<para>This feature is considered dangerous because even if all the required files are signed with the

keys being loaded, some files necessary for the system to function properly still won't be. This

is especially the case with Option ROMs (e.g. for storage controllers or graphics cards). See

<ulink url="https://github.com/Foxboron/sbctl/wiki/FAQ#option-rom">Secure Boot and Option ROMs</ulink>

for more details.</para>

<xi:include href="version-info.xml" xpointer="v252"/></listitem>

</varlistentry>

<varlistentry>

<term>reboot-for-bitlocker</term>

<listitem><para>Caveat: This feature is experimental, and is likely to be changed (or removed in its

current form) in a future version of systemd.</para>

<para>Work around BitLocker requiring a recovery key when the boot loader was

updated (disabled by default).</para>

<para>Try to detect BitLocker encrypted drives along with an active TPM. If both are found and

Windows Boot Manager is selected in the boot menu, set the <literal>BootNext</literal> EFI variable

and restart the system. The firmware will then start Windows Boot Manager directly, leaving the TPM

PCRs in expected states so that Windows can unseal the encryption key. This allows

<citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry> to

be updated without having to provide the recovery key for BitLocker drive unlocking.</para>

<para>Note that the PCRs that Windows uses can be configured with the

<literal>Configure TPM platform validation profile for native UEFI firmware configurations</literal>

group policy under <literal>Computer Configuration\Administrative Templates\Windows Components\BitLocker Drive Encryption</literal>.

When Secure Boot is enabled, changing this to PCRs <literal>0,2,7,11</literal> should be safe.

The TPM key protector needs to be removed and then added back for the PCRs on an already

encrypted drive to change. If PCR 4 is not measured, this setting can be disabled to speed

up booting into Windows.</para>

<xi:include href="version-info.xml" xpointer="v251"/></listitem>

</varlistentry>

</variablelist>

</refsect1>

<refsect1>

<title>Example</title>

<programlisting># /boot/efi/loader/loader.conf

timeout 0

default 01234567890abcdef1234567890abdf0-*

editor no

</programlisting>

<para>The menu will not be shown by default (the menu can still be shown by

pressing and holding a key during boot). One of the entries with files with a

name starting with <literal>01234567890abcdef1234567890abdf0-</literal> will be

selected by default. If more than one entry matches, the one with the highest

priority will be selected (generally the one with the highest version number).

The editor will be disabled, so it is not possible to alter the kernel command

line.</para>

</refsect1>

<refsect1>

<title>See Also</title>

<para><simplelist type="inline">

<member><citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>

<member><citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>

</simplelist></para>

</refsect1>

</refentry>