Bootpartition

A boot partition is a disk partition that contains the files required to start an operating system, including the bootloader, kernel images, and initial ramdisk. It may be a separate partition or reside within the root filesystem. The purpose is to provide a dedicated location that the system firmware or bootloader can access early in the startup sequence.

On legacy BIOS systems with MBR partitioning, the boot partition is often an active primary partition that the firmware loads at power-on. Modern systems using UEFI with GPT typically rely on an EFI System Partition (ESP), usually formatted as FAT32 and flagged boot and esp, which stores the Boot Manager and other necessary drivers before the operating system boots.

Contents typically found in a boot partition include the bootloader program (such as GRUB, LILO, or Windows Boot Manager), kernel images (for example, vmlinuz), initial ramdisk or initramfs images, system maps, and boot configuration files (such as grub.cfg or boot.ini). The exact files depend on the operating system and bootloader in use.

In Linux, /boot is commonly a separate partition mounted at /boot, while on UEFI systems the ESP is mounted at /boot/efi. The ESP provides a standard location for bootloaders independent of the main OS filesystem. A boot partition is often smaller than the root filesystem, sometimes ranging from a few hundred megabytes to a couple of gigabytes, and may use ext2/EXT4 (for /boot) or FAT32 (for ESP).

Windows installations may use a System Reserved partition to hold the Boot Configuration Data and boot manager files, separate from the main Windows partition. Caution is advised when modifying boot partitions, as errors can render a system unbootable.