Lennart Poettering
6718ba1769
We need to store state persistently for the software TPM (i.e. the root key). But given that TPMs are generally used to unlock the rootfs, this storage cannot be on the rootfs. Hence let's use the ESP instead, as the next best thing, that is guaranteed to exist during early boot, given we just were booted from it. This defines automatic logic for this, but does not cause the ESP mount job to be enqueued (since typically we don't actually want that mounted), this is left for the actual services that needs to be done. Note that the mount here is set up quite differently from the one from the host: since initrds are short-lived anyway, it seemed pointless to use autofs. Moreover this uses a fixed place to mount the ESP, inspired by the /sysroot/ + /sysusr/ mount naming. All that to simplify things a bit for the consumers (which is mostly swtpm)
455 lines
28 KiB
XML
455 lines
28 KiB
XML
<?xml version="1.0"?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="systemd-gpt-auto-generator" conditional='HAVE_BLKID'
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>systemd-gpt-auto-generator</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-gpt-auto-generator</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-gpt-auto-generator</refname>
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<refpurpose>Generator for automatically discovering and mounting root, <filename>/home/</filename>,
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<filename>/srv/</filename>, <filename>/var/</filename> and <filename>/var/tmp/</filename> partitions, as
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well as discovering and enabling swap partitions, based on GPT partition type GUIDs</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>/usr/lib/systemd/system-generators/systemd-gpt-auto-generator</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><filename>systemd-gpt-auto-generator</filename> is a unit generator that automatically discovers
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the root partition, <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename>,
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<filename>/var/tmp/</filename>, the EFI System Partition (ESP), the Extended Boot Loader Partition
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(XBOOTLDR), and swap partitions and creates mount and swap units for them, based on the partition type
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GUIDs of GUID partition tables (GPT). See <ulink url="https://uefi.org/specifications">UEFI
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Specification</ulink>, chapter 5 for more details. It implements the <ulink
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url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">UAPI.2 Discoverable
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Partitions Specification</ulink>.</para>
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<para>Note that this generator has no effect on non-GPT systems. It will also not create mount point
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configuration for directories which already contain files or if the mount point is explicitly configured
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in <citerefentry
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project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Additionally
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no unit will be created for the ESP or the XBOOTLDR partition if mount entries are found in the
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<filename>/boot/</filename> or <filename>/efi/</filename> hierarchies in <citerefentry
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project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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<para>If the units this generator creates are overridden, for example by units in directories with higher
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precedence, drop-ins and additional dependencies created by this generator might still be used.</para>
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<para>When run in the initial RAM disk (initrd) this generator can automatically search for the root file
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system. Specifically:
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<itemizedlist>
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<listitem><para>It will look for the root partition on the same physical disk where the EFI System
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Partition (ESP) is located. Note that support from the boot loader is required for this to work: the
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EFI variable <varname>LoaderDevicePartUUID</varname> of the
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<constant>4a67b082-0a4c-41cf-b6c7-440b29bb8c4f</constant> vendor UUID is used to determine from which
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partition (and hence disk) the system was booted. If the boot loader does not set this variable, this
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generator will not be able to detect the root partition. See the <ulink
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url="https://systemd.io/BOOT_LOADER_INTERFACE">Boot Loader Interface</ulink> for
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details.</para></listitem>
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<listitem><para>Alternatively, it will look for the root file system on a loopback block device whose
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<literal>.lo_name</literal> field is set to one of the literal strings <literal>rootdisk</literal> or
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<literal>rootdisk.raw</literal>. This field can be set via <command>losetup</command>'s
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<option>--loop-ref=</option> string. For images downloaded via
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<citerefentry><refentrytitle>systemd-import-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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make sure to set the <literal>blockdev</literal> option and set the local name string to
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<literal>rootdisk</literal> to achieve this effect. Note that discovery of the root file system on
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loopback block devices like this is only done if <literal>root=gpt-auto</literal> or
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<literal>root=dissect</literal> is specified explicitly on the kernel command line, unlike the
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discovery based on the boot loader reported ESP which is also enabled if no <literal>root=</literal>
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parameter is specified at all. (The latter relies on <command>systemd-udevd.service</command>'s
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<filename>/dev/gpt-auto-root</filename> block device symlink generation).</para></listitem>
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<listitem><para>It will also generate a unit file mounting the EFI System Partition (ESP) to
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<filename>/sysefi/</filename>, if applicable. Unlike the file systems mentioned above this mount is not
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activated by default however, but can be pulled in by services requiring ESP access from within the
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initrd. Note that this mount point is initrd-specific and does not make use of autofs. The ESP is
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typically mounted at a different place and via autofs once the system transitions out of the
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initrd.</para></listitem>
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</itemizedlist>
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</para>
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<para>When run on the host system (i.e. after successfully transitioning out of the initrd into the root
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filesystem) this generator will look for all other partitions on the same physical disk as the root
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partition. For this discovery, boot loader support is not required. Moreover, it is not required that the
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root partition was automatically discovered by the initrd (as described above) for the discovery of the
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non-root file partitions to take place. Or in other words: automatic discovery of the root file system
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and of the non-root file systems are independent operations, that do not rely on each other, and are done
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during two distinct phases of the boot process (one in the initrd, the other after). These partitions will
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not be searched for on systems where the root file system is distributed on multiple disks, for example
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via btrfs RAID.</para>
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<para>The root partition can be configured explicitly by symlinking
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<filename>/run/systemd/volatile-root</filename> to <filename>/dev/block/$major:$minor</filename>. This is
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especially useful if the root mount has been replaced by some form of volatile file system
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(overlayfs).</para>
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<para><filename>systemd-gpt-auto-generator</filename> is useful for centralizing file system
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configuration in the partition table and making configuration in <filename>/etc/fstab</filename> or on
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the kernel command line unnecessary.</para>
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<para>This generator looks for the partitions based on their
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partition type GUID. The following partition type GUIDs are
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identified:</para>
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<table>
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<title>Partition Type GUIDs</title>
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<tgroup cols='5' align='left' colsep='1' rowsep='1'>
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<colspec colname="type" />
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<colspec colname="guid" />
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<colspec colname="name" />
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<colspec colname="where" />
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<colspec colname="explanation" />
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<thead>
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<row>
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<entry>Partition Type</entry>
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<entry>GUID</entry>
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<entry>Name</entry>
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<entry>Mount Point</entry>
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<entry>Explanation</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><constant>SD_GPT_ROOT_X86_64</constant></entry>
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<entry><constant>4f68bce3-e8cd-4db1-96e7-fbcaf984b709</constant></entry>
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<entry><filename>Root Partition (x86-64)</filename></entry>
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<entry><filename>/</filename></entry>
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<entry>The first partition with this type UUID, located on the same disk as the ESP used for booting, is used as the root file system <filename>/</filename> on AMD64 / 64-bit x86 systems.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_ROOT_ARM64</constant></entry>
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<entry><constant>b921b045-1df0-41c3-af44-4c6f280d3fae</constant></entry>
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<entry><filename>Root Partition (64-bit ARM)</filename></entry>
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<entry><filename>/</filename></entry>
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<entry>The first partition with this type UUID, located on the same disk as the ESP used for booting, is used as the root file system <filename>/</filename> on AArch64 / 64-bit ARM systems.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_ROOT_ALPHA</constant> <constant>SD_GPT_ROOT_ARC</constant> <constant>SD_GPT_ROOT_ARM</constant> <constant>SD_GPT_ROOT_ARM64</constant> <constant>SD_GPT_ROOT_IA64</constant> <constant>SD_GPT_ROOT_LOONGARCH64</constant> <constant>SD_GPT_ROOT_MIPS</constant> <constant>SD_GPT_ROOT_MIPS64</constant> <constant>SD_GPT_ROOT_MIPS_LE</constant> <constant>SD_GPT_ROOT_MIPS64_LE</constant> <constant>SD_GPT_ROOT_PARISC</constant> <constant>SD_GPT_ROOT_PPC</constant> <constant>SD_GPT_ROOT_PPC64</constant> <constant>SD_GPT_ROOT_PPC64_LE</constant> <constant>SD_GPT_ROOT_RISCV32</constant> <constant>SD_GPT_ROOT_RISCV64</constant> <constant>SD_GPT_ROOT_S390</constant> <constant>SD_GPT_ROOT_S390X</constant> <constant>SD_GPT_ROOT_TILEGX</constant> <constant>SD_GPT_ROOT_X86</constant> <constant>SD_GPT_ROOT_X86_64</constant> <constant>SD_GPT_USR_ALPHA</constant> <constant>SD_GPT_USR_ARC</constant> <constant>SD_GPT_USR_ARM</constant> <constant>SD_GPT_USR_IA64</constant> <constant>SD_GPT_USR_LOONGARCH64</constant> <constant>SD_GPT_USR_MIPS_LE</constant> <constant>SD_GPT_USR_MIPS64_LE</constant> <constant>SD_GPT_USR_PARISC</constant> <constant>SD_GPT_USR_PPC</constant> <constant>SD_GPT_USR_PPC64</constant> <constant>SD_GPT_USR_PPC64_LE</constant> <constant>SD_GPT_USR_RISCV32</constant> <constant>SD_GPT_USR_RISCV64</constant> <constant>SD_GPT_USR_S390</constant> <constant>SD_GPT_USR_S390X</constant> <constant>SD_GPT_USR_TILEGX</constant> <constant>SD_GPT_USR_X86</constant></entry>
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<entry>…</entry>
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<entry>Root partitions for other architectures</entry>
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<entry><filename>/</filename></entry>
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<entry>The first partition with the type UUID matching the architecture, located on the same disk as the ESP used for booting, is used as the root file system <filename>/</filename>. For the full list and constant values, see <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">UAPI.2 Discoverable Partitions Specification</ulink>.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_HOME</constant></entry>
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<entry><constant>933ac7e1-2eb4-4f13-b844-0e14e2aef915</constant></entry>
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<entry>Home Partition</entry>
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<entry><filename>/home/</filename></entry>
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<entry>The first partition with this type UUID on the same disk as the root partition is mounted to <filename>/home/</filename>.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_SRV</constant></entry>
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<entry><constant>3b8f8425-20e0-4f3b-907f-1a25a76f98e8</constant></entry>
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<entry>Server Data Partition</entry>
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<entry><filename>/srv/</filename></entry>
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<entry>The first partition with this type UUID on the same disk as the root partition is mounted to <filename>/srv/</filename>.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_VAR</constant></entry>
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<entry><constant>4d21b016-b534-45c2-a9fb-5c16e091fd2d</constant></entry>
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<entry>Variable Data Partition</entry>
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<entry><filename>/var/</filename></entry>
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<entry>The first partition with this type UUID on the same disk as the root partition is mounted to <filename>/var/</filename> — under the condition its partition UUID matches the first 128 bit of the HMAC-SHA256 of the GPT type uuid of this partition keyed by the machine ID of the installation stored in <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This can be generated using <citerefentry><refentrytitle>systemd-id128</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_TMP</constant></entry>
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<entry><constant>7ec6f557-3bc5-4aca-b293-16ef5df639d1</constant></entry>
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<entry>Temporary Data Partition</entry>
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<entry><filename>/var/tmp/</filename></entry>
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<entry>The first partition with this type UUID on the same disk as the root partition is mounted to <filename>/var/tmp/</filename>.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_SWAP</constant></entry>
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<entry><constant>0657fd6d-a4ab-43c4-84e5-0933c84b4f4f</constant></entry>
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<entry>Swap</entry>
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<entry>n/a</entry>
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<entry>All partitions with this type UUID on the same disk as the root partition are used as swap.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_ESP</constant></entry>
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<entry><constant>c12a7328-f81f-11d2-ba4b-00a0c93ec93b</constant></entry>
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<entry>EFI System Partition (ESP)</entry>
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<entry><filename>/efi/</filename> or <filename>/boot/</filename> once the system transitioned out of the initrd, <filename>/sysefi/</filename> before</entry>
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<entry>The first partition with this type UUID located on the same disk as the root partition is mounted to <filename>/boot/</filename> or <filename>/efi/</filename>, see below.</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_XBOOTLDR</constant></entry>
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<entry><constant>bc13c2ff-59e6-4262-a352-b275fd6f7172</constant></entry>
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<entry>Extended Boot Loader Partition</entry>
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<entry><filename>/boot/</filename></entry>
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<entry>The first partition with this type UUID located on the same disk as the root partition is mounted to <filename>/boot/</filename>, see below.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>This generator understands the following attribute flags for partitions:</para>
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<table>
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<title>Partition Attribute Flags</title>
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<tgroup cols='4' align='left' colsep='1' rowsep='1'>
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<colspec colname="flag" />
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<colspec colname="value" />
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<colspec colname="where" />
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<colspec colname="explanation" />
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<thead>
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<row>
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<entry>Flag</entry>
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<entry>Value</entry>
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<entry>Applicable to</entry>
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<entry>Explanation</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><constant>SD_GPT_FLAG_READ_ONLY</constant></entry>
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<entry><constant>0x1000000000000000</constant></entry>
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<entry><filename>/</filename>, <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename>, <filename>/var/tmp/</filename>, Extended Boot Loader Partition</entry>
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<entry>Partition is mounted read-only</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_FLAG_NO_AUTO</constant></entry>
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<entry><constant>0x8000000000000000</constant></entry>
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<entry><filename>/</filename>, <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename>, <filename>/var/tmp/</filename>, Extended Boot Loader Partition</entry>
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<entry>Partition is not mounted automatically</entry>
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</row>
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<row>
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<entry><constant>SD_GPT_FLAG_NO_BLOCK_IO_PROTOCOL</constant></entry>
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<entry><constant>0x0000000000000002</constant></entry>
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<entry>EFI System Partition (ESP)</entry>
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<entry>Partition is not mounted automatically</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>The <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename>,
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<filename>/var/tmp/</filename> and swap partitions may be encrypted in LUKS format. In this case, a
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device mapper device is set up under the names <filename>/dev/mapper/home</filename>,
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<filename>/dev/mapper/srv</filename>, <filename>/dev/mapper/var</filename>,
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<filename>/dev/mapper/tmp</filename> or <filename>/dev/mapper/swap</filename>. Note that this might
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create conflicts if the same partition is listed in <filename>/etc/crypttab</filename> with a different
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device mapper device name.</para>
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<para>When systemd is running in the initrd the <filename>/</filename> partition may be encrypted with
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LUKS as well. In this case, a device mapper device is set up under the name
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<filename>/dev/mapper/root</filename>, and a <filename>sysroot.mount</filename> is set up that mounts the
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device under <filename>/sysroot</filename>. For more information, see
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<citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
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</para>
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<para>Mount and automount units for the EFI System Partition (ESP) and Extended Boot Loader Partition
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(XBOOTLDR) are generated on EFI systems. If the disk contains an XBOOTLDR partition, as defined in the
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<ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">UAPI.1 Boot Loader
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Specification</ulink>, it is made available at <filename>/boot/</filename>. This generator creates an
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automount unit; the mount will only be activated on-demand when accessed. The mount point will be created
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if necessary.</para>
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<para>The ESP is mounted to <filename>/boot/</filename> if that directory exists and is not used for
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XBOOTLDR, and otherwise to <filename>/efi/</filename>. Same as for <filename>/boot/</filename>, an
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automount unit is used. The mount point will be created if necessary. These apply once the system
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transitioned out of the initrd phase. Before that, if components in the initrd require ESP access, it
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will be mounted to <filename>/sysefi/</filename>.</para>
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<para>No configuration is created for mount points that are configured in <citerefentry
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project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry> or when
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the target directory contains files.</para>
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<para>When using this generator in conjunction with btrfs file
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systems, make sure to set the correct default subvolumes on them,
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using <command>btrfs subvolume set-default</command>.</para>
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<para>If the system was booted via
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<citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> and the
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stub reported to userspace that the kernel image was measured to a TPM2 PCR, then any discovered root and
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<filename>/var/</filename> volume identifiers (and volume encryption keys, in case they are encrypted)
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will be automatically measured into PCR 15 on activation, via
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<citerefentry><refentrytitle>systemd-pcrfs@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. Moreover,
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information about the LUKS key slot used to unlock the volume is measured into NvPCR
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<literal>cryptsetup</literal>. Finally, if the root or <filename>/usr/</filename> partition is protected
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via Verity its root hash and the serial/issuer of the key used for the provided root hash signature (if
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any) are measured into the NvPCR <literal>verity</literal>.</para>
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<para>Mount constraint metadata contained in the file systems is validated by pulling in
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<citerefentry><refentrytitle>systemd-validatefs@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for generated mounts.</para>
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<para><filename>systemd-gpt-auto-generator</filename> implements
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<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>Kernel Command Line</title>
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<para><filename>systemd-gpt-auto-generator</filename> understands the following kernel command line
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parameters:</para>
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<variablelist class='kernel-commandline-options'>
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<varlistentry>
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<term><varname>systemd.gpt_auto</varname></term>
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<term><varname>rd.systemd.gpt_auto</varname></term>
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<listitem><para>Those options take an optional boolean argument, and default to yes.
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The generator is enabled by default, and a false value may be used to disable it
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(e.g. <literal>systemd.gpt_auto=0</literal>).
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</para>
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<xi:include href="version-info.xml" xpointer="v242"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>systemd.image_policy=</varname></term>
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|
|
<listitem><para>Takes an image dissection policy string as argument (as per
|
|
<citerefentry><refentrytitle>systemd.image-policy</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
|
|
and allows enforcing a policy on dissection and use of the automatically discovered GPT partition
|
|
table entries.</para>
|
|
|
|
<para>Note that the specified image policy is not taken into account for automatic root or
|
|
<filename>/usr/</filename> file system discovery unless
|
|
<varname>root=dissect</varname>/<varname>mount.usr=dissect</varname> (or
|
|
<varname>root=dissect-force</varname>) are specified. (The policy will always be applied to the other
|
|
auto-discoverable partition types.)</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v254"/></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>systemd.image_filter=</varname></term>
|
|
|
|
<listitem><para>Takes an image dissection filter string as argument (as per
|
|
<citerefentry><refentrytitle>systemd.image-filter</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
|
|
and allows enforcing a set of globbing patterns on the partition matching of the automatically
|
|
discovered GPT partition table entries.</para>
|
|
|
|
<para>Note that the specified image filter is not taken into account for automatic root or
|
|
<filename>/usr/</filename> file system discovery unless
|
|
<varname>root=dissect</varname>/<varname>mount.usr=dissect</varname> (or
|
|
<varname>root=dissect-force</varname>) are specified. (The filter will always be applied to the other
|
|
auto-discoverable partition types.)</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v258"/></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>root=</varname></term>
|
|
<term><varname>rootfstype=</varname></term>
|
|
<term><varname>rootflags=</varname></term>
|
|
|
|
<listitem><para>When <varname>root=</varname> is used with the special value
|
|
<literal>gpt-auto</literal>, basic automatic discovery of the root partition based on the GPT
|
|
partition type is enabled. Use of the root partition is delayed until factory reset mode is left, in
|
|
case it is enabled during the current boot. See <ulink url="https://systemd.io/FACTORY_RESET">Factory
|
|
Reset</ulink> for more information on that. If <literal>gpt-auto-force</literal> is specified
|
|
automatic discovery of the root partition is enabled, ignoring any factory reset mode.</para>
|
|
|
|
<para>If <varname>root=</varname> is set to the special value <literal>dissect</literal> full
|
|
automatic discovery of the root partition based on GPT partition information is enabled. This is a
|
|
superset of <varname>root=gpt-auto</varname>, as it automatically configures Verity partitions
|
|
(including signature-based setup) following the logic defined for that in the <ulink
|
|
url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification/">UAPI.2 Discoverable
|
|
Partitions Specification</ulink>. Moreover it takes the configured image policy and image filter into
|
|
account for all partition types, including the root file system. <literal>root=dissect</literal> will
|
|
wait for the factory reset phase to be completed if it is in effect before activating the root file
|
|
system. Use <literal>root=dissect-force</literal> to ignore the factory reset phase and activate the
|
|
root file system immediately.</para>
|
|
|
|
<para>Any other value (i.e. besides <literal>gpt-auto</literal>, <literal>gpt-auto-force</literal>,
|
|
<literal>dissect</literal>, <literal>dissect-force</literal>) disables automatic root file system
|
|
discovery.</para>
|
|
|
|
<para>If <varname>root=</varname> is not specified at all on the kernel command line automatic
|
|
discovery of the root partition via the ESP reported by the boot loader is also enabled (taking
|
|
factory reset state into account, i.e. equivalent to <literal>root=gpt-auto</literal>), however in
|
|
this case discovery based on the loopback block device <literal>.lo_name</literal> field is not
|
|
enabled.</para>
|
|
|
|
<para>The <varname>rootfstype=</varname> and <varname>rootflags=</varname> options are used to select
|
|
the file system type and options when the root file system is automatically discovered.</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v242"/></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>mount.usr=</varname></term>
|
|
<term><varname>mount.usrfstype=</varname></term>
|
|
<term><varname>mount.usrflags=</varname></term>
|
|
|
|
<listitem><para>Similar to <varname>root=</varname>, <varname>rootfstype=</varname>,
|
|
<varname>rootflags=</varname> (see above), but applies to the <filename>/usr/</filename> partition
|
|
instead. Note that the <literal>gpt-auto</literal>, <literal>gpt-auto-force</literal>,
|
|
<literal>dissect-force</literal> settings that <filename>root=</filename> understands are not
|
|
supported by <varname>mount.usr=</varname> (however <literal>dissect</literal> is).</para>
|
|
|
|
<para>Also note that automatic partition discovery for <filename>/usr/</filename> must be enabled
|
|
explicitly, unlike the discovery for the root file system, which is enabled if no
|
|
<varname>root=</varname> parameter is passed at all.</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v258"/></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>rw</varname></term>
|
|
<term><varname>ro</varname></term>
|
|
|
|
<listitem><para>Mount the root partition read-write or read-only <emphasis>initially</emphasis>.</para>
|
|
|
|
<para>Note that unlike most kernel command line options these settings do not override configuration
|
|
in the file system, and the file system may be remounted later. See
|
|
<citerefentry><refentrytitle>systemd-remount-fs.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
|
|
</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v242"/></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>systemd.swap=</varname></term>
|
|
|
|
<listitem><para>Takes a boolean argument or enables the option if specified without an argument.
|
|
If disabled, automatic discovery of swap partition(s) based on GPT partition type is disabled.
|
|
Defaults to enabled.</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v254"/></listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
<para><simplelist type="inline">
|
|
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd-pcrfs@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd-validatefs@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
|
|
<member><citerefentry project='url'><refentrytitle url='https://btrfs.readthedocs.io/en/latest/btrfs.html'>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
|
|
</refentry>
|