GNU GRUB

GNU GRUB (GRand Unified Bootloader) is a free and open source project that provides users with an easy-to-install-and-configure boot loader software for booting a single or multiple operating systems that are installed on a personal computer or laptop.

Key features include support for real memory management, internationalization support, portability, support for cross-platform installations, compact core image, support for dynamic loading to the core image, as well as a object-oriented framework.

The program has been used for many years now on a wide range of GNU/Linux systems, allowing users to easily and quickly switch between multiple OSes installed on one of multiple disk drives of a computer.

It supports a wide range of operating systems, including GNU/Linux, BSD, Solaris, as well as Microsoft Windows. In addition, it can be installed on Master boot record (MBR), GUID Partition Table (GPT) and Unified Extensible Firmware Interface (UEFI).

The software is comprised of different utilities, including grub-setup, grub-install, grub-mkconfig and update-grub. A standard GRUB installation will require users to run only the grub-install command with certain options, as well as the grub-mkconfig command.

Its default configuration file is usually located under /boot/grub/grub.cfg, but the best way to edit its settings is to open the /etc/defaults/grub file with any text editor and run the update-grub command, as root (system administrator).

As the computer technologies advance and BIOS-based systems disappear, the GNU GRUB boot loader tries to keep up with them, but it is slowly replaced by modern and more simplistic boot loaders, such as Syslinux, Gummiboot, rEFInd, rEFIt, and many others that are specifically designed for UEFI systems.

All in all, GNU GRUB is the next generation of the GRand Unified Bootloader, adopted by 95 percent of current GNU/Linux operating systems. It can be easily installed on an existing Linux/UNIX OS, replacing the current boot loader.

What is new in this release:

• New/improved filesystem and disk support:
• Big-endian UFS1.
• Experimental 64-bit ext2 support.
• Various fixes for non-512-byte sector devices.
• New `proc' filesystem framework, used by LUKS disks.
• Fix DM-RAID partition handling.
• New `nativedisk' command to switch from firmware to native disk drivers.
• Compressed HFS+.
• DragonFly BSD labels.
• CBFS (coreboot).
• Handle partitioned LVM properly.
• Use LVM UUIDs whenever possible.
• GPT PReP.
• New `progress' module that shows progress information while reading files.
• ZFS features support.
• ZFS LZ4 support.
• XFS V5 format support.
• LVM RAID1 support.
• New/improved terminal and video support:
• Monochrome text (matching `hercules' in GRUB Legacy).
• Morse code output using system speaker.
• `spkmodem' output (simple data protocol using system speaker).
• Handle Japanese special keys.
• coreboot framebuffer.
• Serial on ARC.
• Native vt100 handling for grub-emu, replacing the use of the curses library.
• New gfxmenu options for terminal window positioning, theme background image handling, and scrollbar padding, plus `item_pixmap_style' and `highlight_overlay'.
• Support several more image types (paletted and greyscale).
• Boot protocol improvements:
• Support Apple FAT binaries on non-Apple platforms.
• Improve FreeDOS direct loading support compatibility.
• Enable `linux16' on all x86 platforms, not just BIOS.
• New TrueCrypt ISO loader.
• multiboot2 boot-services EFI specification.
• multiboot2 EFI memory map specification.
• multiboot2 full-file specfication.
• New/improved network support:
• New variables `net_default_*' containing properties of the default interface.
• Autoload `http' and `tftp' modules if necessary.
• Improve TFTP robustness.
• Parse `nd' disk names in GRUB Legacy configuration files.
• Issue separate DNS queries for IPv4 and IPv6.
• Support IPv6 Router Advertisement to configure default router.
• New variable net__next_server containing next server from BOOTP reply.
• Coreboot improvements:
• CBFS support both in on-disk images (loopback) and flash.
• Ability to launch another payload from flash or disk
• Coreboot framebuffer
• CBMEMC support (both logging and inspecting logs)
• Command for inspecting coreboot timestamps (`coreboot_boottime').
• Command for inspecting coreboot tables (`lscoreboot').
• New target default_payload.elf.
• Increased maximal core size.
• Prefer pmtimer for TSC calibration.
• New/improved platform support:
• New `efifwsetup' and `lsefi' commands on EFI platforms.
• New `cmosdump' and `cmosset' commands on platforms with CMOS support.
• New command `pcidump' for PCI platforms.
• Improve opcode parsing in ACPI halt implementation.
• Use the TSC as a possible time source on i386-ieee1275.
• Merge PowerPC grub-mkrescue implementation with the common one.
• Support grub-mkrescue on i386-ieee1275, sparc64, bootinfo machines such as pSeries, and mips-arc.
• Make grub-mkrescue better support Apple Intel Macs on CD.
• Enable GRUB Legacy configuration file parsing on EFI.
• Support halt for Loongson 2E.
• ARM U-Boot and EFI ports.
• Reorganise platform-dependent code in utilities to avoid #ifdef mess.
• AROS and Haiku support for userspace utilities.
• Xen PV port.
• Fix EFI stack alignment.
• ARM64 EFI port.
• On Linux, read partition start offsets from sysfs if possible.
• New grub-macbless utility, and better integration with Mac firmware in grub-install.
• Support Yeeloong 3A.
• Add `cpuid --pae' option to detect Physical Address Extension on x86.
• Support for USB debug dongles.
• Support for *-emu on all platforms (previously only i386/x86_64 worked).
• Support *-emu on Windows.
• New platform `none' which builds only user level utilities. This is now default if target CPU is not supported.
• Support for booting little-endian Linux kernel on powerpc.
• Support network boot with Oracle sun4v vnet devices.
• Added SAS disks to the IEEE 1275 Open Firmware device list.
• Try multiple methods for TSC (timestamp counter) calibration - PIT, pmtimer, EFI Stall. If everything fails, use hardcoded frequency 800MHz.
• Support Hyper-V Gen2 platforms which lack PIT for TSC calibration.
• Map UEFI Persistent Memory to E820 persistent memory.
• New Xen loader on ARM64.
• Respect alignment requirement for block device IO buffers on EFI.
• Security:
• Add optional facility to enforce that all files read by the core image from disk have a valid detached digital signature.
• Performance:
• Avoid costly division operations in many places.
• New boot time analysis framework (`./configure --enable-boot-time').
• Initialise USB ports in parallel.
• New `testspeed' command to test file read speed.
• Speed-up gfxterm by storing intermediate results in more compact format.
• Lazy LVM/mdraid scan.
• Disk hints.
• Scripting:
• New `eval' and `tr' commands.
• grub-script-check fails on scripts containing no commands.
• Installation and other utility improvements:
• Add option to compress files on installation or image creation.
• Using grub-reboot no longer requires setting `GRUB_DEFAULT=saved'.
• Support probing EFI System Partition (requires os-prober >= 1.58).
• Fix inconsistent use of `GRUB_CRYPTODISK_ENABLE' and `GRUB_ENABLE_CRYPTODISK'; the latter is now used consistently.
• grub-mount handles symbolic links to directories.
• Support disabling submenus with `GRUB_DISABLE_SUBMENU' configuration key for grub-mkconfig.
• grub-install, grub-mknetdir, grub-mkrescue, and grub-mkstandalone rewritten in C. They should now work in supported non-Unix-like environments.
• Native mingw support.
• Ability to install on EFI under windows.
• Reorganise timeout handling using new `timeout_style' environment variable and `GRUB_TIMEOUT_STYLE' configuration key for grub-mkconfig. Menu hotkeys pressed during a hidden timeout now boot the corresponding menu entry immediately.
• New `file' command and grub-file utility to check file types.
• New syslinux configuration file parser.
• Set menu entry class to primary OS name returned by os-prober to display OS specific icon.
• On Linux x86 detect EFI word size in grub-install and automatically select correct platform (x86_64-efi or i386-efi) to install. Requires Linux kernel 4.0 or higher.
• Build system:
• Remove all uses of nested functions; GRUB no longer requires an executable stack.
• Fix documentation build with Texinfo >= 5.1.
• More robust and documented cross-compiling support.
• Partial clang support for some platforms (experimental).
• Partial mingw64 x86_64-efi compile support (highly experimental).
• Partial mingw32 i386-(other than already present i386-pc) compile support (highly experimental).
• Support for grub-mkpasswd on Windows.
• Eliminate the use of AutoGen. This allowed some performance improvements to the build system.
• Remove variable length arrays.
• OpenBSD compile and tools support (NetBSD and FreeBSD were already supported).
• Fix build with FreeType >= 2.5.1.
• Make gentpl.py compatible with Python 3. It now requires at least Python 2.6.
• modinfo.sh contains build information now.
• Added many new tests to improve robustness.
• Target is built without libgcc now. Necessary builtins are reimplemented directly. This removes requirement for target-specific runtime on build system.
• emu libusb support removed (was broken and unmaintained).
• powerpc64le compile support.
• Use fixed timestamp when generating GRUB image for reproducible builds.
• Verify at build time that modules contain only supported relocations and their structure matches what boot-time module loader expects.
• Do not require fonts on powerpc-ieee1275.

What is new in version 2.00 / 2.02 Beta 2:

• New/improved filesystem and disk support:
• Big-endian UFS1.
• Experimental 64-bit ext2 support.
• Various fixes for non-512-byte sector devices.
• New `proc' filesystem framework, used by LUKS disks.
• Fix DM-RAID partition handling.
• New `nativedisk' command to switch from firmware to native disk drivers.
• Compressed HFS+.
• DragonFly BSD labels.
• CBFS (coreboot).
• Handle partitioned LVM properly.
• Use LVM UUIDs whenever possible.
• GPT PReP.
• New `progress' module that shows progress information while reading files.
• ZFS features support.
• ZFS LZ4 support.
• New/improved terminal and video support:
• Monochrome text (matching `hercules' in GRUB Legacy).
• Morse code output using system speaker.
• `spkmodem' output (simple data protocol using system speaker).
• Handle Japanese special keys.
• coreboot framebuffer.
• Serial on ARC.
• Native vt100 handling for grub-emu, replacing the use of the curses library.
• New gfxmenu options for terminal window positioning, theme background image handling, and scrollbar padding, plus `item_pixmap_style' and `highlight_overlay'.
• Support several more image types (paletted and greyscale).
• Boot protocol improvements:
• Support Apple FAT binaries on non-Apple platforms.
• Improve FreeDOS direct loading support compatibility.
• Enable `linux16' on all x86 platforms, not just BIOS.
• New TrueCrypt ISO loader.
• multiboot2 boot-services EFI specification.
• multiboot2 EFI memory map specification.
• multiboot2 full-file specfication.
• New/improved network support:
• New variables `net_default_*' containing properties of the default interface.
• Autoload `http' and `tftp' modules if necessary.
• Improve TFTP robustness.
• Parse `nd' disk names in GRUB Legacy configuration files.
• Issue separate DNS queries for IPv4 and IPv6.
• Coreboot improvements:
• CBFS support both in on-disk images (loopback) and flash.
• Ability to launch another payload from flash or disk
• Coreboot framebuffer
• CBMEMC support (both logging and inspecting logs)
• Command for inspecting coreboot timestamps (`coreboot_boottime').
• Command for inspecting coreboot tables (`lscoreboot').
• New target default_payload.elf.
• Increased maximal core size.
• New/improved platform support:
• New `efifwsetup' and `lsefi' commands on EFI platforms.
• New `cmosdump' and `cmosset' commands on platforms with CMOS support.
• New command `pcidump' for PCI platforms.
• Improve opcode parsing in ACPI halt implementation.
• Use the TSC as a possible time source on i386-ieee1275.
• Merge PowerPC grub-mkrescue implementation with the common one.
• Support grub-mkrescue on i386-ieee1275, sparc64, bootinfo machines such as pSeries, and mips-arc.
• Make grub-mkrescue better support Apple Intel Macs on CD.
• Enable GRUB Legacy configuration file parsing on EFI.
• Support halt for Loongson 2E.
• ARM U-Boot and EFI ports.
• Reorganise platform-dependent code in utilities to avoid #ifdef mess.
• AROS and Haiku support for userspace utilities.
• Xen PV port.
• Fix EFI stack alignment.
• ARM64 EFI port.
• On Linux, read partition start offsets from sysfs if possible.
• New grub-macbless utility, and better integration with Mac firmware in grub-install.
• Support Yeeloong 3A.
• Add `cpuid --pae' option to detect Physical Address Extension on x86.
• Support for USB debug dongles.
• Support for *-emu on all platforms (previously only i386/x86_64 worked).
• Support *-emu on Windows.
• Security:
• Add optional facility to enforce that all files read by the core image from disk have a valid detached digital signature.
• Performance:
• Avoid costly division operations in many places.
• New boot time analysis framework (`./configure --enable-boot-time').
• Initialise USB ports in parallel.
• New `testspeed' command to test file read speed.
• Speed-up gfxterm by storing intermediate results in more compact format.
• Lazy LVM/mdraid scan.
• Disk hints.
• Scripting:
• New `eval' and `tr' commands.
• grub-script-check fails on scripts containing no commands.
• Installation and other utility improvements:
• Add option to compress files on installation or image creation.
• Using grub-reboot no longer requires setting `GRUB_DEFAULT=saved'.
• Support probing EFI System Partition (requires os-prober >= 1.58).
• Fix inconsistent use of `GRUB_CRYPTODISK_ENABLE' and `GRUB_ENABLE_CRYPTODISK'; the latter is now used consistently.
• grub-mount handles symbolic links to directories.
• Support disabling submenus with `GRUB_DISABLE_SUBMENU' configuration key for grub-mkconfig.
• grub-install, grub-mknetdir, grub-mkrescue, and grub-mkstandalone rewritten in C. They should now work in supported non-Unix-like environments.
• Native mingw support.
• Ability to install on EFI under windows.
• Reorganise timeout handling using new `timeout_style' environment variable and `GRUB_TIMEOUT_STYLE' configuration key for grub-mkconfig. Menu hotkeys pressed during a hidden timeout now boot the corresponding menu entry immediately.
• New `file' command and grub-file utility to check file types.
• New syslinux configuration file parser.
• Build system:
• Remove all uses of nested functions; GRUB no longer requires an executable stack.
• Fix documentation build with Texinfo >= 5.1.
• More robust and documented cross-compiling support.
• Partial clang support for some platforms (experimental).
• Partial mingw64 x86_64-efi compile support (highly experimental).
• Partial mingw32 i386-(other than already present i386-pc) compile support (highly experimental).
• Support for grub-mkpasswd on Windows.
• Eliminate the use of AutoGen. This allowed some performance improvements to the build system.
• Remove variable length arrays.
• OpenBSD compile and tools support (NetBSD and FreeBSD were already supported).
• Fix build with FreeType >= 2.5.1.
• Make gentpl.py compatible with Python 3. It now requires at least Python 2.6.
• modinfo.sh contains build information now.
• Added many new tests to improve robustness.
• Revision control moved to git.

What is new in version 1.99:

• Keyboard layouts support.
• Parser for GRUB Legacy configuration files.
• Extend `vbeinfo' and `vbetest' commands to non-VBE graphics, as `videoinfo' and `videotest'.
• New `lsefisystab', `lssal', and `lsefimmap' commands on EFI platforms.
• Support explicit user claim that a device is BIOS-visible. Devices listed in device.map will be assumed to be readable using only BIOS facilities, rather than anything more complex such as LVM or RAID.
• New bash-completion script for GRUB utilities.
• Use ACPI to shut down if possible.
• New `lsacpi' command.
• New `--boot-directory' option to `grub-install', `grub-reboot', and `grub-set-default', with clearer semantics than the previous `--root-directory' option.
• Rename CD-ROM device to "cd" on BIOS platforms.
• Transparent decompression filters.
• Simpler PXE image generation. New `grub-mknetdir' utility to generate netboot directory trees.
• New relocator. Allows for more kernel support and more straightforward loader writing.
• Handle USB pendrives exposed as floppies.
• New Automake-based build system.
• Add `sendkey' command (i386-pc only).
• Support 1.x versions of mdadm metadata.
• Fix corruption when reading Reiserfs directory entries.
• Bidirectional text and diacritics support.
• Change grub-mkdevicemap to emit /dev/disk/by-id/ names where possible on GNU/Linux.
• Add `grub-mkconfig' support for Xen with Linux.
• Add `grub-mkconfig' support for initrd images on Fedora 13.
• Support >3GiB and

What is new in version 1.98:

• Multiboot on EFI support.
• Saved default menu entry support, with new utilities `grub-reboot' and `grub-set-default'.
• Unit testing framework.
• Support for multiple terminals.
• Encrypted password support, with a new utility `grub-mkpasswd-pbkdf2'.
• `grub-mkfloppy' removed; use `grub-mkrescue' to create floppy images.
• Add grub-probe support for GNU/Hurd.
• Add support for gettext.

What is new in version 1.97.1:

• Fixes security issue