Module discoverable_partition_specification

Expand description

Partition type GUIDs from the Discoverable Partitions Specification (DPS)

This module contains constants for partition type GUIDs as defined by the UAPI Group’s Discoverable Partitions Specification.

Reference: https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

§Overview

The Discoverable Partitions Specification (DPS) defines standardized partition type GUIDs that enable automatic discovery and mounting of partitions without explicit configuration. This is a key enabler for bootc’s installation process and for modern systemd-based initramfs implementations.

§How bootc uses DPS

When bootc install to-disk creates partitions, it sets the appropriate DPS partition type GUID based on the target CPU architecture. This enables several important capabilities:

§Automatic root discovery

With a DPS-aware bootloader and initramfs (containing systemd-gpt-auto-generator), the root filesystem can be discovered and mounted automatically without requiring a root= kernel argument. The initramfs:

Reads the EFI LoaderDevicePartUUID variable to identify the boot disk
Scans the GPT for a partition with the architecture-specific root type GUID
Mounts that partition as the root filesystem

§Architecture-specific partition types

Each CPU architecture has its own root partition type GUID. This prevents accidentally booting a system on incompatible hardware. bootc uses this_arch_root to select the correct GUID at compile time.

§Composefs and sealed boot

When using the composefs backend with UKIs (Unified Kernel Images), bootc can omit the root= kernel argument entirely. This enables:

Measured boot: The kernel command line is part of the UKI signature
Simplified image building: No machine-specific kernel arguments needed
systemd-repart integration: Future support for declarative partition management

§Partition types included

This module defines constants for:

Root partitions: Architecture-specific root filesystem partitions
USR partitions: Separate /usr partitions (included for spec completeness; not currently used by bootc)
Verity partitions: dm-verity hash partitions for integrity verification
Verity signature partitions: Signed verity root hashes
Special partitions: ESP, XBOOTLDR, swap, home, var, etc.

§Usage (internal)

This is an internal module. Within bootc, it is used like:

use crate::discoverable_partition_specification::{this_arch_root, ESP};

// Get the root partition type GUID for the current architecture
let root_type: &str = this_arch_root();

// ESP GUID is architecture-independent
let esp_type: &str = ESP;

Constants§

ESP: EFI System Partition (ESP) for UEFI boot
HOME: Home partition (/home)
LINUX_DATA: Generic Linux filesystem data partition
ROOT_ALPHA: Root partition for Alpha architecture
ROOT_ARC: Root partition for ARC architecture
ROOT_ARM: Root partition for 32-bit ARM architecture
ROOT_ARM64: Root partition for 64-bit ARM/AArch64 architecture
ROOT_IA64: Root partition for Itanium/IA-64 architecture
ROOT_LOONGARCH64: Root partition for 64-bit LoongArch architecture
ROOT_MIPS: Root partition for 32-bit MIPS Big Endian
ROOT_MIPS64: Root partition for 64-bit MIPS Big Endian
ROOT_MIPS64_LE: Root partition for 64-bit MIPS Little Endian
ROOT_MIPS_LE: Root partition for 32-bit MIPS Little Endian
ROOT_PARISC: Root partition for PA-RISC/HPPA architecture
ROOT_PPC: Root partition for 32-bit PowerPC
ROOT_PPC64: Root partition for 64-bit PowerPC Big Endian
ROOT_PPC64_LE: Root partition for 64-bit PowerPC Little Endian
ROOT_RISCV32: Root partition for 32-bit RISC-V
ROOT_RISCV64: Root partition for 64-bit RISC-V
ROOT_S390: Root partition for s390 architecture
ROOT_S390X: Root partition for s390x architecture
ROOT_TILEGX: Root partition for TILE-Gx architecture
ROOT_VERITY_ALPHA: Root verity partition for Alpha
ROOT_VERITY_ARC: Root verity partition for ARC
ROOT_VERITY_ARM: Root verity partition for 32-bit ARM
ROOT_VERITY_ARM64: Root verity partition for 64-bit ARM/AArch64
ROOT_VERITY_IA64: Root verity partition for Itanium/IA-64
ROOT_VERITY_LOONGARCH64: Root verity partition for 64-bit LoongArch
ROOT_VERITY_MIPS: Root verity partition for 32-bit MIPS Big Endian
ROOT_VERITY_MIPS64: Root verity partition for 64-bit MIPS Big Endian
ROOT_VERITY_MIPS64_LE: Root verity partition for 64-bit MIPS Little Endian
ROOT_VERITY_MIPS_LE: Root verity partition for 32-bit MIPS Little Endian
ROOT_VERITY_PARISC: Root verity partition for PA-RISC
ROOT_VERITY_PPC: Root verity partition for 32-bit PowerPC
ROOT_VERITY_PPC64: Root verity partition for 64-bit PowerPC Big Endian
ROOT_VERITY_PPC64_LE: Root verity partition for 64-bit PowerPC Little Endian
ROOT_VERITY_RISCV32: Root verity partition for 32-bit RISC-V
ROOT_VERITY_RISCV64: Root verity partition for 64-bit RISC-V
ROOT_VERITY_S390: Root verity partition for s390
ROOT_VERITY_S390X: Root verity partition for s390x
ROOT_VERITY_SIG_ALPHA: Root verity signature partition for Alpha
ROOT_VERITY_SIG_ARC: Root verity signature partition for ARC
ROOT_VERITY_SIG_ARM: Root verity signature partition for 32-bit ARM
ROOT_VERITY_SIG_ARM64: Root verity signature partition for 64-bit ARM/AArch64
ROOT_VERITY_SIG_IA64: Root verity signature partition for Itanium/IA-64
ROOT_VERITY_SIG_LOONGARCH64: Root verity signature partition for 64-bit LoongArch
ROOT_VERITY_SIG_MIPS: Root verity signature partition for 32-bit MIPS Big Endian
ROOT_VERITY_SIG_MIPS64: Root verity signature partition for 64-bit MIPS Big Endian
ROOT_VERITY_SIG_MIPS64_LE: Root verity signature partition for 64-bit MIPS Little Endian
ROOT_VERITY_SIG_MIPS_LE: Root verity signature partition for 32-bit MIPS Little Endian
ROOT_VERITY_SIG_PARISC: Root verity signature partition for PA-RISC
ROOT_VERITY_SIG_PPC: Root verity signature partition for 32-bit PowerPC
ROOT_VERITY_SIG_PPC64: Root verity signature partition for 64-bit PowerPC Big Endian
ROOT_VERITY_SIG_PPC64_LE: Root verity signature partition for 64-bit PowerPC Little Endian
ROOT_VERITY_SIG_RISCV32: Root verity signature partition for 32-bit RISC-V
ROOT_VERITY_SIG_RISCV64: Root verity signature partition for 64-bit RISC-V
ROOT_VERITY_SIG_S390: Root verity signature partition for s390
ROOT_VERITY_SIG_S390X: Root verity signature partition for s390x
ROOT_VERITY_SIG_TILEGX: Root verity signature partition for TILE-Gx
ROOT_VERITY_SIG_X86: Root verity signature partition for 32-bit x86
ROOT_VERITY_SIG_X86_64: Root verity signature partition for 64-bit x86/AMD64
ROOT_VERITY_TILEGX: Root verity partition for TILE-Gx
ROOT_VERITY_X86: Root verity partition for 32-bit x86
ROOT_VERITY_X86_64: Root verity partition for 64-bit x86/AMD64
ROOT_X86: Root partition for 32-bit x86
ROOT_X86_64: Root partition for 64-bit x86/AMD64
SRV: Server data partition (/srv)
SWAP: Swap partition
TMP: Temporary data partition (/var/tmp)
USR_ALPHA: /usr partition for Alpha architecture
USR_ARC: /usr partition for ARC architecture
USR_ARM: /usr partition for 32-bit ARM
USR_ARM64: /usr partition for 64-bit ARM/AArch64
USR_IA64: /usr partition for Itanium/IA-64
USR_LOONGARCH64: /usr partition for 64-bit LoongArch
USR_MIPS: /usr partition for 32-bit MIPS Big Endian
USR_MIPS64: /usr partition for 64-bit MIPS Big Endian
USR_MIPS64_LE: /usr partition for 64-bit MIPS Little Endian
USR_MIPS_LE: /usr partition for 32-bit MIPS Little Endian
USR_PARISC: /usr partition for PA-RISC
USR_PPC: /usr partition for 32-bit PowerPC
USR_PPC64: /usr partition for 64-bit PowerPC Big Endian
USR_PPC64_LE: /usr partition for 64-bit PowerPC Little Endian
USR_RISCV32: /usr partition for 32-bit RISC-V
USR_RISCV64: /usr partition for 64-bit RISC-V
USR_S390: /usr partition for s390
USR_S390X: /usr partition for s390x
USR_TILEGX: /usr partition for TILE-Gx
USR_VERITY_ALPHA: /usr verity partition for Alpha
USR_VERITY_ARC: /usr verity partition for ARC
USR_VERITY_ARM: /usr verity partition for 32-bit ARM
USR_VERITY_ARM64: /usr verity partition for 64-bit ARM/AArch64
USR_VERITY_IA64: /usr verity partition for Itanium/IA-64
USR_VERITY_LOONGARCH64: /usr verity partition for 64-bit LoongArch
USR_VERITY_MIPS: /usr verity partition for 32-bit MIPS Big Endian
USR_VERITY_MIPS64: /usr verity partition for 64-bit MIPS Big Endian
USR_VERITY_MIPS64_LE: /usr verity partition for 64-bit MIPS Little Endian
USR_VERITY_MIPS_LE: /usr verity partition for 32-bit MIPS Little Endian
USR_VERITY_PARISC: /usr verity partition for PA-RISC
USR_VERITY_PPC: /usr verity partition for 32-bit PowerPC
USR_VERITY_PPC64: /usr verity partition for 64-bit PowerPC Big Endian
USR_VERITY_PPC64_LE: /usr verity partition for 64-bit PowerPC Little Endian
USR_VERITY_RISCV32: /usr verity partition for 32-bit RISC-V
USR_VERITY_RISCV64: /usr verity partition for 64-bit RISC-V
USR_VERITY_S390: /usr verity partition for s390
USR_VERITY_S390X: /usr verity partition for s390x
USR_VERITY_SIG_ALPHA: /usr verity signature partition for Alpha
USR_VERITY_SIG_ARC: /usr verity signature partition for ARC
USR_VERITY_SIG_ARM: /usr verity signature partition for 32-bit ARM
USR_VERITY_SIG_ARM64: /usr verity signature partition for 64-bit ARM/AArch64
USR_VERITY_SIG_IA64: /usr verity signature partition for Itanium/IA-64
USR_VERITY_SIG_LOONGARCH64: /usr verity signature partition for 64-bit LoongArch
USR_VERITY_SIG_MIPS: /usr verity signature partition for 32-bit MIPS Big Endian
USR_VERITY_SIG_MIPS64: /usr verity signature partition for 64-bit MIPS Big Endian
USR_VERITY_SIG_MIPS64_LE: /usr verity signature partition for 64-bit MIPS Little Endian
USR_VERITY_SIG_MIPS_LE: /usr verity signature partition for 32-bit MIPS Little Endian
USR_VERITY_SIG_PARISC: /usr verity signature partition for PA-RISC
USR_VERITY_SIG_PPC: /usr verity signature partition for 32-bit PowerPC
USR_VERITY_SIG_PPC64: /usr verity signature partition for 64-bit PowerPC Big Endian
USR_VERITY_SIG_PPC64_LE: /usr verity signature partition for 64-bit PowerPC Little Endian
USR_VERITY_SIG_RISCV32: /usr verity signature partition for 32-bit RISC-V
USR_VERITY_SIG_RISCV64: /usr verity signature partition for 64-bit RISC-V
USR_VERITY_SIG_S390: /usr verity signature partition for s390
USR_VERITY_SIG_S390X: /usr verity signature partition for s390x
USR_VERITY_SIG_TILEGX: /usr verity signature partition for TILE-Gx
USR_VERITY_SIG_X86: /usr verity signature partition for 32-bit x86
USR_VERITY_SIG_X86_64: /usr verity signature partition for 64-bit x86/AMD64
USR_VERITY_TILEGX: /usr verity partition for TILE-Gx
USR_VERITY_X86: /usr verity partition for 32-bit x86
USR_VERITY_X86_64: /usr verity partition for 64-bit x86/AMD64
USR_X86: /usr partition for 32-bit x86
USR_X86_64: /usr partition for 64-bit x86/AMD64
VAR: Variable data partition (/var)
XBOOTLDR: Extended Boot Loader Partition

Functions§

this_arch_root: Returns the root partition GUID for the current architecture.