[[GRUB]]'sThe '''BIOS boot partition''' is a [[partition (computing)|partition]] on a [[data storage device]] that [[GNU GRUB]] uses on legacy [[BIOS]]-based systems[[personal computer]]s in order to [[Booting|boot]] an [[operating system]], when the actual [[boot device]] contains a [[GUID Partition Table]] (GPT). Such a layout is sometimes referred to as BIOS-GPT boot.
ItA BIOS boot partition is needed because GPT uses the [[disk sector|sectors]]s immediately following the [[Master Boot Record]] (MBR) to hold the actual partition table, (whereas the traditional MBR-based partitioning scheme doesn'tdoes not designate them for anything)any special purpose. As a result, makingthere itis unavailablenot toenough holdunused thespace codeavailable thefor storing second stages of [[boot loader]]s needson toGPT loaddisks; inboot orderloaders toare readusually fromimplemented aso [[filesystem]].their code (Thestored space available inwithin the MBR, iswhich severelycannot limitedhold more than (<512 bytes), sooperates theas codea storedfirst therestage isn'tthat reallyserves ableprimarily to doload anythinga more complicated thansecond loadingstage, awhich largeris, blockfor example, capable of codereading fromand aloading simple-to-findan ___location[[operating onsystem diskkernel]] andfrom runa that[[file system]].)