Gdisk - Grub2 Device Image System Kit

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Gdisk is a bootable multiboot USB manager built on pure GRUB2 scripting - on the same path as Ventoy, GrubFM and Easy2Boot, but designed to be transparent, hackable and centred around GRUB2. There are no opaque binaries: every menu, scan and boot handler is a readable .cfg you can inspect and modify.

Custom GRUB modules extracted from GrubFM have been patched to allow raw .iso and .img loopback booting in UEFI mode, and the boot chain installs a patched a1ive core.img for hybrid BIOS + UEFI support from a single device.

Latest release: v3.2 - the whole utility has been updated and optimized, and a new portable Linux & windows installers is available.

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Features

• Pure GRUB2 scripting - no closed binaries; the whole menu system is editable text
• Hybrid BIOS + UEFI - one device boots on legacy CSM and modern UEFI machines
• Raw ISO / IMG loopback boot - direct UEFI booting of .iso and .img files
• Dynamic pre-boot menus - loopback-mounts an image, detects the OS, and offers the right boot paths automatically
• Fast ISO scanner - speed-optimised scan of every partition for bootable images
• Partition & directory browser - walks each partition and routes every file type to the correct boot handler
• WIM / WinPE booting - .wim and WinPE boot on both UEFI (grubfm wimboot) and BIOS, plus a native Windows Boot Manager loader
• VHD / VHDX booting - native NT6+ boot of .vhd and .vhdx via ntloader on both UEFI and BIOS, plus raw disk-mapping fallbacks (map, grub4dos, memdisk) for fixed VHDs. See "VHD / VHDX boot" below for the NTFS requirement.
• vDiskChain - auto-scans all partitions for .vtoy disk images and chainloads them
• Live-system entries - direct boot menus for Glitch Linux, Bonsai and other live distros
• Bundled loaders - rEFInd, agFM (grubfm) and an iPXE network-boot framework under EFI/
• Flexible installers - portable Linux GUI installer, Linux CLI installer, Windows installer and iPXE network install, with selectable disk layouts (FAT32, FAT32 + NTFS, FAT32 + exFAT)
• Self-contained installers - the CLI and Windows installers also ship inside the device itself (boot/Gdisk-Installer/)

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Installing Gdisk

There are four ways to install Gdisk onto a target USB drive or disk. The Linux GUI installer is the recommended starting point.

Method 1 - Linux GUI Installer (gdisk-v3.2-gui-linux)

Image	Format	Description
gdisk-v3.2-gui-linux	Portable Linux Binary	GUI Installer

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A graphical installer for Linux. It is a single portable binary, so there is nothing to install and no dependencies to set up first. Make it executable and launch it with sudo:

chmod +x gdisk-v3.2-gui-linux
sudo ./gdisk-v3.2-gui-linux

Root is required because the installer partitions, formats and writes boot code to the target disk. It drives the same Create, Update and Repair operations and the same disk layouts as the CLI installer below.

Method 2 - Linux CLI Installer (gdisk-v3-installer.sh)

Image	Format	Description
gdisk-v3.2-installer.sh	Linux Bash Script	Interactive CLI Installer

An interactive CLI installer that runs on any Linux system with GRUB2 tools available. Downloads the latest Gdisk files from GitHub and deploys them to the target device. Must be run as root:

chmod +x gdisk-v3-installer.sh
sudo ./gdisk-v3-installer.sh

Requirements: Linux with git, parted, mkfs.vfat, rsync, grub-bios-setup (from grub-pc-bin). Missing tools are detected and the installer offers to install them with your package manager (apt, dnf, yum, pacman or zypper). The NTFS and exFAT layouts additionally need mkfs.ntfs (ntfs-3g) or mkfs.exfat.

Three operations are available:

• Create - Wipe a whole disk, create a new MBR partition table with the layout of your choice (see below), deploy all Gdisk files, and install the BIOS + UEFI boot chain.
• Update - Install or refresh Gdisk onto an existing partition. Existing user data is preserved, Gdisk boot files are added/overwritten.
• Repair - Reinstall the MBR core.img and/or UEFI BOOTX64.EFI on an existing Gdisk device without touching user data. Useful when the boot chain is broken but your ISOs and other files are fine.

Disk layouts for Create:

Layout	Partitions
Pure FAT32	Single FAT32 partition across the whole disk
FAT32 + NTFS	32 MB Gdisk-EFI FAT32 partition + Gdisk-Ntfs data partition (custom size or rest of disk)
FAT32 + exFAT	32 MB Gdisk-EFI FAT32 partition + Gdisk-exFAT data partition (custom size or rest of disk)

In the two hybrid layouts the small FAT32 partition holds the GRUB modules and BOOTX64.EFI, while the data partition holds your boot images (ISO / IMG / WIM / VHD). Use FAT32 + NTFS if you want native VHD / VHDX boot, which requires NTFS. Both hybrid layouts also avoid the 4 GiB single-file limit of FAT32.

Method 3 - Windows Installer (gdisk-v3-installer.exe)

Image	Format	Description
gdisk-v3-installer.exe	Portable Windows Executable	GUI Installer

A portable GUI installer for Windows and WinPE. Everything is self-contained - wget.exe, 7z.exe and a cross-compiled grub-bios-setup.exe are all embedded. No installation or external dependencies required.

The installer fetches the latest Gdisk build from GitHub, partitions and formats the target with diskpart, deploys the files, and installs the BIOS + UEFI boot chain. Works on physical drives and mounted virtual disks - anything diskpart can see.

Operations:

• Create Gdisk device - Format the target disk as MBR/FAT32 and deploy Gdisk
• Update / Repair - Reinstall the MBR boot chain and refresh boot files (boot/ and EFI/), preserving user data

Note: Run as Administrator. In WinPE, the installer works out of the box since WinPE runs with full privileges.

Method 4 - iPXE Network Boot (no local media needed)

Image	Format	Description
Gdisk-ISO-v3.2-Installer-iPXE.iso	Bootable ISO	iPXE boots minimal buildroot linux and then auto-launches gdisk cli installer

For situations where you don't have a working Linux or Windows environment available, or you want to install Gdisk to the same disk you're booting from.

iPXE images boot a minimal buildroot live system entirely into RAM via network boot. Once booted, the Gdisk installer runs automatically. Because the OS is running from RAM, the target disk is completely free - you can install Gdisk to the very disk you booted from.

Requirements: Wired internet connection (Ethernet). The iPXE boot image must be flashed to a USB stick or disk first using any raw image writer (dd, Rufus, Etcher, etc) OR launch the .iso in a virtual machine with wifi so ethernet is virtualized. OR burn it to a cd/dvd and boot bare-metal.

iPXE install workflow:

1. Download the iPXE ISO image
2. Launch in Virtual-Machine OR:
3. Flash it to a USB stick using dd, Rufus, Etcher or similar:

   sudo dd if=Gdisk-ISO-v3.2-iPXE.iso of=/dev/sdX bs=4M status=progress

4. Boot the target machine from the USB stick (BIOS or UEFI)
5. The system network-boots a minimal buildroot live environment into RAM
6. The Gdisk installer (gdisk-v3.sh) starts automatically
7. Select your target disk - this can be the same USB stick you booted from, since the live system is running entirely from RAM
8. The installer downloads and deploys Gdisk to the target

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Booting

Boot the target device in either BIOS/CSM or UEFI mode. The primary menu opens on Browse Partitions; from there you can walk partitions and directories, and Gdisk routes each .iso, .img, .wim, .vhd, .vhdx or .vtoy to the appropriate pre-boot handler.

Supported boot formats

Gdisk can directly boot the following file types from any attached partition:

Format	Description
.iso	CD/DVD images - Linux, Windows, utilities
.img	Raw disk images
.wim	Windows Imaging Format / WinPE
.vhd / .vhdx	Virtual hard disks (Windows native boot)
.vtoy	Ventoy-compatible disk images (vDiskChain)
.efi	UEFI executables and shell applications

Bundled bootloaders

Gdisk ships with custom versions of several well-known bootloaders and network-boot tools, all accessible from the main menu:

• agFM (a1ive GrubFM) - file manager and boot helper with patched GRUB2 modules for raw ISO/IMG loopback in UEFI
• rEFInd - graphical UEFI boot manager for multi-OS setups
• Ventoy - vDiskChain support for .vtoy disk images
• netboot.xyz - iPXE-based network boot framework for installing or booting dozens of operating systems over the network

VHD / VHDX boot

Drop .vhd or .vhdx files into the root, /VHD/ or /Gdisk/ of any attached partition and pick VHD / VHDX Boot from the main menu, or reach them through the browser or the Quickboot menu.

Boot methods offered per image:

Method	Platform	Container support
ntloader (preferred)	BIOS + UEFI	fixed and dynamic VHD, VHDX
ntloader ram= (load to RAM)	BIOS + UEFI	fixed and dynamic VHD, VHDX
ntboot --vhd (native NT6+ boot)	UEFI + BIOS	fixed and dynamic VHD, VHDX
map --type=HD / map -f	UEFI	fixed VHD only
grub4dos map	BIOS	fixed VHD only
memdisk raw (loads to RAM)	BIOS	fixed VHD only
vDiskChain	UEFI + BIOS	fixed VHD only

Native boot uses the Windows Boot Manager, so two host-volume constraints apply:

• The VHD should live on an NTFS volume. bootmgr attaches the VHD with its own filesystem drivers plus bootvhd.dll, and does not mount VHDs from FAT32 or exFAT.
• FAT32 caps single files at 4 GiB. Gdisk's own partition is FAT32, so anything larger than 4 GiB has to sit on a separate NTFS partition. The installer's FAT32 + NTFS layout provides this out of the box.

Why ntloader is preferred for BIOS

On UEFI, bootmgfw.efi has VHD support compiled in. On BIOS, bootmgr must load \boot\bootvhd.dll to attach the VHD, and Windows boot modules are version-locked: a mismatched bootmgr / bootvhd.dll pair is rejected with Windows Boot Manager status 0xc0000098 (STATUS_FILE_INVALID). ntloader ships its own initrd.cpio containing a matched 10.0.20348 set (bootmgr.exe, bootvhd.dll, boot.sdi, bootx64.efi), which avoids the problem entirely.

The ntboot entries remain as a fallback. They use bootmgr-nt11.exe (10.0.22621.2283) paired with bootvhd.dll (10.0.22621.1555) rather than the older bootmgr.exe (10.0.19041.1), which is kept only for the BIOS WIM boot path.

Supporting files live in boot/grub/ntloader/ (ntloader binaries plus initrd.cpio) and boot/grub/wimboot/ (wimboot.xz holding bootmgfw.efi for UEFI, plus bootmgr.exe, bootmgr-nt11.exe, bootvhd.dll and boot.sdi for BIOS).

You can also test a device without rebooting using the bundled QEMU launcher. It boots the physical disk Gdisk is installed on and asks whether to use BIOS (SeaBIOS) or UEFI (OVMF):

./Qemu-Boot.sh     # choose BIOS or UEFI (UEFI requires: apt install ovmf)

The standalone qemu-bios.sh and qemu-uefi.sh scripts remain in boot/Gdisk-Scripts/.

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Building an ISO

boot/Gdisk-Mkiso/ contains scripts to build a bootable Gdisk .iso (including a hybrid BIOS + UEFI El Torito image recognised by Rufus):

sudo bash boot/Gdisk-Mkiso/mkiso-auto-custom.sh

Layout

Gdisk/
├── boot/
│   ├── grub/                           GRUB2 core: modules, theme, images, and all menu logic
│   │   ├── grub.cfg                    entry point - hands off to gdisk.cfg
│   │   ├── gdisk.cfg                   main menu (v3.2)
│   │   ├── gdisk-partitions.cfg        "Browse Partitions" partition list
│   │   ├── gdisk-browse.cfg            directory browser
│   │   ├── gdisk-boot.cfg              dynamic loader for .iso .img .wim .vhd .vhdx .vtoy
│   │   ├── iso-preboot.cfg             ISO pre-boot menu (loopback + OS detection)
│   │   ├── img-preboot.cfg             IMG pre-boot menu (loopback + analysis)
│   │   ├── wim-preboot.cfg             WIM pre-boot menu
│   │   ├── vhd-preboot.cfg             VHD/VHDX pre-boot menu (ntloader, ntboot, raw maps)
│   │   ├── iso-scan.cfg                speed-optimised ISO scanner
│   │   ├── vhd-scan.cfg                .vhd/.vhdx auto-scan across all partitions
│   │   ├── wimdiskchain.cfg            dynamic WIM boot scanner (all partitions)
│   │   ├── wimboot-scan.cfg            wimboot payload with dynamic .wim discovery
│   │   ├── winpe-native.cfg            native Windows Boot Manager / WinPE loader
│   │   ├── winpe-iso.cfg               WinPE ISO boot menu
│   │   ├── vdiskchain.cfg              .vtoy disk-image auto-scan and chainload
│   │   ├── glitch-live.cfg             Glitch Linux live boot
│   │   ├── linux-live.cfg              Linux live system boot entries
│   │   ├── grub-ipxe.cfg               Glitch iPXE multi-net-boot (UEFI / BIOS)
│   │   ├── system.cfg                  System menu
│   │   ├── release.cfg                 disclaimer / banner screen
│   │   ├── iso-boot.cfg  iso-menu.cfg  legacy v2.0 ISO menus (not linked from main menu)
│   │   ├── boot-local-efi.cfg          boot local EFI loader from 1st drive (unlinked helper)
│   │   ├── i386-pc/                    BIOS modules + patched core-patched.img / boot.img
│   │   ├── x86_64-efi/                 UEFI modules
│   │   ├── ntloader/                   ntloader v3.0.7 + initrd.cpio (NT6+ VHD/VHDX/WIM)
│   │   ├── agFM/  theme/  images/  fonts/  locale/  wimboot/  vdiskchain/   supporting assets
│   │   └── efi.img  font.pf2  grubenv
│   ├── Gdisk-Installer/                CLI, Windows and GUI installers (+ payload helpers)
│   ├── Gdisk-Mkiso/                    ISO-build scripts (gdisk-mkiso.sh + custom variants)
│   └── Gdisk-Scripts/                  QEMU launchers, grub4dos generator, WIM converters, download helpers
├── EFI/
│   ├── BOOT/BOOTX64.EFI                patched grubfm UEFI boot binary
│   ├── grubfm/                         agFM loader (grubfmx64.efi)
│   ├── refind/                         rEFInd boot manager
│   └── iPXE/                           iPXE network-boot binary (Glitch-iPXE.efi)
├── Gdisk/                              drop folder for bootable files (.iso .img .vtoy .wim .vhd .vhdx .ima)
├── Qemu-Boot.sh                        boot this device in QEMU (BIOS or UEFI)
├── autorun.inf
├── Gdisk.ico
└── README.md

Release Downloads - v3.2

File	Use it for	Size
gdisk-v3.2-gui-linux	Recommended. Graphical installer, portable binary	40.2 MB
gdisk-v3.2-cli-linux	Command-line installer, portable binary	0.1 MB
gdisk-v3.2-installer.sh	Command-line installer (bash script)	44.6 KB
gdisk-v3-installer.exe	Windows portable GUI installer (v3.0, FAT32 only)	11.4 MB
Gdisk-ISO-v3.2.iso	Full bootable image with complete Gdisk repo	177.7 MB
Gdisk-ISO-v3.2-installer.iso	Minimal Buildroot Linux Gdisk installer	43.7 MB
Gdisk-ISO-v3.2-iPXE.iso	iPXE network-boot to full Gdisk ISO	3.0 MB
Gdisk-ISO-v3.2-Installer-iPXE.iso	iPXE network-boot to minimal Buildroot Gdisk installer	3.0 MB

Checksums (SHA-256)

94eb081b5e9a0b5ec647e5d71ad342d1c2d4930488ed93bbf75c627b091e2da9  gdisk-v3.2-gui-linux
4bf402e0f991d1f831e0dd2225a4b1af1635b9e7cb21eac3f3a8174508ca1712  gdisk-v3.2-cli-linux
3959f5f6dfca11c40940d463e9dded2df6009ac844eb2100e6b7285c06ce7cb3  gdisk-v3.2-installer.sh
59f16167b993e3d9f4b43802586cc3984b3e252780c0eabecdc87f0b8d2c93ae  gdisk-v3-installer.exe
9a8f699083225aa25d6a48779aa2856634622852ad226bf76fe0dd2b8805088f  Gdisk-ISO-v3.2.iso
c56359f4d4419e9d0c05793b19c5feb2aefc4fde52e62344e9564de5d72e6a87  Gdisk-ISO-v3.2-installer.iso
0e3d5c71a035746c347293f60f2f1e3a1af2cc74ea8d816884d17ec48a004a19  Gdisk-ISO-v3.2-iPXE.iso
c6af1e58d3cf3546d1a1843c9b5c632a0b934faa2b80ffb3737e307f53807051  Gdisk-ISO-v3.2-Installer-iPXE.iso

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Source: https://github.com/GlitchLinux · Glitch::blog https://glitchlinux.com/blog · GPLv3