BIOS boot partition: Difference between revisions

Revision as of 15:59, 23 November 2017

Revision as of 06:00, 5 May 2018

Line 20:

| accessdate = 2014-06-26

| website = gnu.org

}}</ref> (which, when written to a GPT in the required little endian fields, forms the ASCII string "<tt>Hah!IdontNeedEFIhaHdInotNeedEFI</tt>").<!-- See talk page for some notes on endianness confusion. --> In the context of GPT on a BIOS-based computer, a BIOS boot partition is similar in some respects to the [[EFI System partition]], which is used by systems based on [[Extensible Firmware Interface|EFI]]. The EFI System partition holds a filesystem and files used by the UEFI, while the BIOS boot partition is used in BIOS-based systems and accessed without a filesystem by holding raw binary code.

The size requirements for a BIOS boot partition are quite low so it can be as small as about 30&nbsp;KiB; however, as future boot loaders might require more space, 1&nbsp;MiB might be a reasonable BIOS boot partition size. Due to the [[1 MB partition alignment|1&nbsp;MiB partition alignment]] policies used by most modern disk partitioning tools to provide optimum performance with [[Advanced Format]] disks, [[Solid-state drive|SSD devices]] and certain [[RAID]] configurations, some room is left allowing the placement of a BIOS boot partition between the GPT and the first partition aligned that way. If created by utilizing that free space, the BIOS boot partition would be out of the GPT alignment specification, but that is not very important{{cn|date=June 2017|reason=Who says it is unimportant? Is this just opinion or is it declared in the partitioning standard / bootloader's documentation? Even if it is *written* to rarely, it is *read* every boot, and anything that clobbers it will prevent the system from being able to boot.}} since it is written to very infrequently.