BIOS boot partition: Difference between revisions

Revision as of 15:53, 4 May 2015

Revision as of 15:54, 4 May 2015

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== Overview ==

[[File:GNU GRUB components.svg|thumb|upright=12.8|In the example 2 above, [[GRUB 2]] stores its {{Mono|core.img}} in a BIOS boot partition.]]

When used, the BIOS boot partition contains the second stage of the [[boot loader]] program, such as the [[GRUB&nbsp;2]]; the first stage is the code that is contained within the [[Master Boot Record]] (MBR). Use of this partition is not the only way BIOS-based boot can be performed while using GPT-partitioned hard drives; however, complex boot loaders such as [[GRUB 2]] cannot fit entirely within the confines of the MBR's 398<!-- MBR with disk timestamp, disk signature, AAP and NEWLDR support --> to 446<!-- classic MBR without any extensions --> bytes of space, thus they need an ancillary storage space. On MBR disks, such boot loaders typically use the sectors immediately following the MBR for this storage; that space is usually known as the "MBR gap". No equivalent unused space exists on GPT disks, and the BIOS boot partition is a way to officially allocate such space for use by the boot loader.