doc: slightly reorder/improve partition type table

Let's put swap and generic linux data partitions next to each other, and
clarify they predated this spec.
This commit is contained in:
Lennart Poettering 2021-04-21 18:12:25 +02:00
parent 1d6ca0a219
commit eb3c3a89c9

View file

@ -73,10 +73,10 @@ Interface](https://systemd.io/BOOT_LOADER_INTERFACE).
| `3b8f8425-20e0-4f3b-907f-1a25a76f98e8` | _Server Data Partition_ | Any native, optionally in LUKS | The first partition with this type UUID on the disk containing the root partition is automatically mounted to `/srv/`. If the partition is encrypted with LUKS, the device mapper file will be named `/dev/mapper/srv`. |
| `4d21b016-b534-45c2-a9fb-5c16e091fd2d` | _Variable Data Partition_ | Any native, optionally in LUKS | The first partition with this type UUID on the disk containing the root partition is automatically mounted to `/var/` — under the condition that its partition UUID matches the first 128 bit of `HMAC-SHA256(machine-id, 0x4d21b016b53445c2a9fb5c16e091fd2d)` (i.e. the SHA256 HMAC hash of the binary type UUID keyed by the machine ID as read from [`/etc/machine-id`](https://www.freedesktop.org/software/systemd/man/machine-id.html). This special requirement is made because `/var/` (unlike the other partition types listed here) is inherently private to a specific installation and cannot possibly be shared between multiple OS installations on the same disk, and thus should be bound to a specific instance of the OS, identified by its machine ID. If the partition is encrypted with LUKS, the device mapper file will be named `/dev/mapper/var`. |
| `7ec6f557-3bc5-4aca-b293-16ef5df639d1` | _Temporary Data Partition_ | Any native, optionally in LUKS | The first partition with this type UUID on the disk containing the root partition is automatically mounted to `/var/tmp/`. If the partition is encrypted with LUKS, the device mapper file will be named `/dev/mapper/tmp`. Note that the intended mount point is indeed `/var/tmp/`, not `/tmp/`. The latter is typically maintained in memory via <tt>tmpfs</tt> and does not require a partition on disk. In some cases it might be desirable to make `/tmp/` persistent too, in which case it is recommended to make it a symlink or bind mount to `/var/tmp/`, thus not requiring its own partition type UUID. |
| `0657fd6d-a4ab-43c4-84e5-0933c84b4f4f` | _Swap_ | Swap | All swap partitions on the disk containing the root partition are automatically enabled. |
| `0657fd6d-a4ab-43c4-84e5-0933c84b4f4f` | _Swap_ | Swap | All swap partitions on the disk containing the root partition are automatically enabled. This partition type predates the Discoverable Partitions Specification. |
| `0fc63daf-8483-4772-8e79-3d69d8477de4` | _Generic Linux Data Partitions_ | Any native, optionally in LUKS | No automatic mounting takes place for other Linux data partitions. This partition type should be used for all partitions that carry Linux file systems. The installer needs to mount them explicitly via entries in <tt>/etc/fstab</tt>. Optionally, these partitions may be encrypted with LUKS. This partition type predates the Discoverable Partitions Specification. |
| `c12a7328-f81f-11d2-ba4b-00a0c93ec93b` | _EFI System Partition_ | VFAT | The ESP used for the current boot is automatically mounted to `/efi/` (or `/boot/` as fallback), unless a different partition is mounted there (possibly via `/etc/fstab`, or because the Extended Boot Loader Partition — see below — exists) or the directory is non-empty on the root disk. This partition type is defined by the [UEFI Specification](http://www.uefi.org/specifications). |
| `bc13c2ff-59e6-4262-a352-b275fd6f7172` | _Extended Boot Loader Partition_ | Typically VFAT | The Extended Boot Loader Partition (XBOOTLDR) used for the current boot is automatically mounted to <tt>/boot/</tt>, unless a different partition is mounted there (possibly via <tt>/etc/fstab</tt>) or the directory is non-empty on the root disk. This partition type is defined by the [Boot Loader Specification](https://systemd.io/BOOT_LOADER_SPECIFICATION). |
| `0fc63daf-8483-4772-8e79-3d69d8477de4` | _Other Data Partitions_ | Any native, optionally in LUKS | No automatic mounting takes place for other Linux data partitions. This partition type should be used for all partitions that carry Linux file systems. The installer needs to mount them explicitly via entries in <tt>/etc/fstab</tt>. Optionally, these partitions may be encrypted with LUKS. |
Other GPT type IDs might be used on Linux, for example to mark software RAID or
LVM partitions. The definitions of those GPT types is outside of the scope of