SYSTEMD-GPT-AUTO-GENERATORsystemd-gpt-auto-generaSYSTEMD-GPT-AUTO-GENERATOR(8)
NAME
systemd-gpt-auto-generator - Generator for automatically discovering
and mounting root, /home and /srv partitions, as well as discovering
and enabling swap partitions, based on GPT partition type GUIDs.
SYNOPSIS
/usr/lib/systemd/system-generators/systemd-gpt-auto-generator
DESCRIPTION
systemd-gpt-auto-generator is a unit generator that automatically
discovers root, /home, /srv and swap partitions and creates mount and
swap units for them, based on the partition type GUIDs of GUID
partition tables (GPT), see UEFI Specification[1], chapter 5. It
implements the Discoverable Partitions Specification[2]. Note that this
generator has no effect on non-GPT systems, or where the directories
under the mount points are already non-empty. Also, on systems where
the units are explicitly configured (for example, listed in fstab(5)),
the units this generator creates are overridden, but additional
implicit dependencies might be created.
This generator will only look for root partitions on the same physical
disk the EFI System Partition (ESP) is located on. It will only look
for the other partitions on the same physical disk the root file system
is located on. These partitions will not be searched for on systems
where the root file system is distributed on multiple disks, for
example via btrfs RAID.
systemd-gpt-auto-generator is useful for centralizing file system
configuration in the partition table and making configuration in
/etc/fstab unnecessary.
This generator looks for the partitions based on their partition type
GUID. The following partition type GUIDs are identified:
Table 1. Partition Type GUIDs
+-------------------------------------+-----------------+---------------------+
|Partition Type GUID | Name | Explanation |
+-------------------------------------+-----------------+---------------------+
|44479540-f297-41b2-9af7-d131d5f0458a | Root Partition | On 32-bit x86 |
| | (x86) | systems, the first |
| | | x86 root partition |
| | | on the disk the EFI |
| | | ESP is located on |
| | | is mounted to the |
| | | root directory /. |
+-------------------------------------+-----------------+---------------------+
|4f68bce3-e8cd-4db1-96e7-fbcaf984b709 | Root Partition | On 64-bit x86 |
| | (x86-64) | systems, the first |
| | | x86-64 root |
| | | partition on the |
| | | disk the EFI ESP is |
| | | located on is |
| | | mounted to the root |
| | | directory /. |
+-------------------------------------+-----------------+---------------------+
|69dad710-2ce4-4e3c-b16c-21a1d49abed3 | Root Partition | On 32-bit ARM |
| | (32-bit ARM) | systems, the first |
| | | ARM root partition |
| | | on the disk the EFI |
| | | ESP is located on |
| | | is mounted to the |
| | | root directory /. |
+-------------------------------------+-----------------+---------------------+
|b921b045-1df0-41c3-af44-4c6f280d3fae | Root Partition | On 64-bit ARM |
| | (64-bit ARM) | systems, the first |
| | | ARM root partition |
| | | on the disk the EFI |
| | | ESP is located on |
| | | is mounted to the |
| | | root directory /. |
+-------------------------------------+-----------------+---------------------+
|993d8d3d-f80e-4225-855a-9daf8ed7ea97 | Root Partition | On Itanium systems, |
| | (Itanium/IA-64) | the first Itanium |
| | | root partition on |
| | | the disk the EFI |
| | | ESP is located on |
| | | is mounted to the |
| | | root directory /. |
+-------------------------------------+-----------------+---------------------+
|933ac7e1-2eb4-4f13-b844-0e14e2aef915 | Home Partition | The first home |
| | | partition on the |
| | | disk the root |
| | | partition is |
| | | located on is |
| | | mounted to /home. |
+-------------------------------------+-----------------+---------------------+
|3b8f8425-20e0-4f3b-907f-1a25a76f98e8 | Server Data | The first server |
| | Partition | data partition on |
| | | the disk the root |
| | | partition is |
| | | located on is |
| | | mounted to /srv. |
+-------------------------------------+-----------------+---------------------+
|0657fd6d-a4ab-43c4-84e5-0933c84b4f4f | Swap | All swap partitions |
| | | located on the disk |
| | | the root partition |
| | | is located on are |
| | | enabled. |
+-------------------------------------+-----------------+---------------------+
|c12a7328-f81f-11d2-ba4b-00a0c93ec93b | EFI System | The first ESP |
| | Partition (ESP) | located on the disk |
| | | the root partition |
| | | is located on is |
| | | mounted to /boot or |
| | | /efi, see below. |
+-------------------------------------+-----------------+---------------------+
This generator understands the following attribute flags for
partitions:
Table 2. Partition Attributes
+------------------------------+--------------------+----------------+------------------+
|Name | Value | Applicable to | Explanation |
+------------------------------+--------------------+----------------+------------------+
|GPT_FLAG_READ_ONLY | 0x1000000000000000 | /, /srv, /home | Partition is |
| | | | mounted |
| | | | read-only |
+------------------------------+--------------------+----------------+------------------+
|GPT_FLAG_NO_AUTO | 0x8000000000000000 | /, /srv, /home | Partition is not |
| | | | mounted |
| | | | automatically |
+------------------------------+--------------------+----------------+------------------+
|GPT_FLAG_NO_BLOCK_IO_PROTOCOL | 0x0000000000000002 | ESP | Partition is not |
| | | | mounted |
| | | | automatically |
+------------------------------+--------------------+----------------+------------------+
The /home and /srv partitions may be encrypted in LUKS format. In this
case, a device mapper device is set up under the names /dev/mapper/home
and /dev/mapper/srv. Note that this might create conflicts if the same
partition is listed in /etc/crypttab with a different device mapper
device name.
Mount and automount units for the EFI System Partition (ESP) are
generated on EFI systems. The ESP is mounted to /boot, unless a mount
point directory /efi exists, in which case it is mounted there. Since
this generator creates an automount unit, the mount will only be
activated on-demand, when accessed. On systems where /boot (or /efi if
it exists) is an explicitly configured mount (for example, listed in
fstab(5)) or where the /boot (or /efi) mount point is non-empty, no
mount units are generated.
When using this generator in conjunction with btrfs file systems, make
sure to set the correct default subvolumes on them, using btrfs
subvolume set-default.
systemd-gpt-auto-generator implements systemd.generator(7).
SEE ALSO
systemd(1), systemd.mount(5), systemd.swap(5), systemd-fstab-
generator(8), systemd-cryptsetup@.service(8), cryptsetup(8), fstab(5),
btrfs(8)
NOTES
1. UEFI Specification
http://www.uefi.org/specifications
2. Discoverable Partitions Specification
https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/
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