Slim64FS Disk Identity (GPT + MBR)

This document defines how to label Slim64FS partitions and how to verify them.

Canonical IDs

GPT type GUID (primary): 64646464-6464-4464-8464-82F63B786464
MBR type byte (legacy): 0x64

Precedence Rule

Partition table IDs are advisory metadata.

Slim64FS runtime truth is determined by filesystem superblock validation (S64_SUPER_MAGIC, S64_SUPER_VERSION) and checker/tool inspection.

If partition metadata conflicts with on-disk Slim64FS format, superblock validation wins.

Create Partition Labels

GPT (recommended)

Using sgdisk:

# example device
DEV=/dev/sdX

# create GPT and one partition
sgdisk --zap-all "$DEV"
sgdisk --new=1:0:0 "$DEV"
sgdisk --typecode=1:64646464-6464-4464-8464-82F63B786464 "$DEV"
sgdisk --change-name=1:slim64fs "$DEV"

Using parted:

DEV=/dev/sdX
parted -s "$DEV" mklabel gpt
parted -s "$DEV" mkpart slim64fs 1MiB 100%

(parted may not know custom GUID aliases; set exact GUID with sgdisk.)

MBR (legacy)

Using fdisk interactively:

fdisk /dev/sdX
  o        # new DOS label
  n        # new partition
  p        # primary
  1        # partition number
  <enter>  # first sector
  <enter>  # last sector
  t        # set type
  64       # hex type 0x64
  w        # write

Verify Partition Metadata

lsblk -o NAME,PATH,PTTYPE,PARTTYPE,FSTYPE,SIZE /dev/sdX
blkid /dev/sdX1
parted -s /dev/sdX print
fdisk -l /dev/sdX

Expected:

GPT path: PARTTYPE should show 64646464-6464-4464-8464-82f63b786464
MBR path: partition type should show 0x64

Verify Filesystem Truth

After formatting the partition/image with Slim64FS:

slim64fs-info /dev/sdX1
slim64fs-check /dev/sdX1

These tools verify on-disk Slim64FS structures directly and are authoritative for runtime compatibility.

Release Guidance

For public releases:

Use GPT GUID as the canonical identity in docs/examples.
Keep MBR 0x64 documented as legacy compatibility hint.
Publish both partition-metadata verification and superblock verification commands in release notes.