Article translation fromwiki, Limited level, If there is any mistake, please forgive me. original text:https://en.wikipedia.org/wiki/BIOS_boot_partition
<https://en.wikipedia.org/wiki/BIOS_boot_partition>

 

BIOS boot partition It's a partition,gnu grub[ Translation and annotation1]
<https://www.cnblogs.com/f-ck-need-u/p/7084627.html#blogf1> Use it to guide based onlegacy
bios But the boot device containsGPT Operating system when formatting partitioned tables. This structure is sometimes calledBIOS/GPT start-up[ Translation and annotation2]
<https://www.cnblogs.com/f-ck-need-u/p/7084627.html#blogf2>.

The figure below is not the original, Provided by myself, For intuitive feelingbios boot partition.



Bios
boot Zoning is necessary, becauseGPT Use the followingMBR The following sectors hold the actual partition table, But in the traditionalMBR In partition schema, These sectors have no special purpose, As a result, there is not enough free space to storestage2 This paragraphboot
loader.MBR Also stored inboot loader, butMBR Cannot store more than512 Contents of bytes, thereforeMBR This paragraphboot
loader Be treated asstage1 Use, Its main function is to load more and more complex functionsstage2 This paragraphboot loader,stage2 The operating system kernel can be read and loaded from the file system.

  When usedBIOS boot partition, The section will containstage2 Ofboot loader program, for examplegrub2 file, andstage1 Ofboot
loader Code remains inMBR in. Usebios boot Partitioning is not a solution based on traditionbios But it is used.gpt The only way to solve the problem of format disk, But it's complicatedboot
loader asgrub2 Can't fully matchMBR Medium398-446 Byte area, So they need a secondary storage space. stayMBR On disk, General use follows closelyMBR To store these complexboot
loader, These sector spaces are well known"MBR gap". While inGPT On disk, Because there is no relationship betweenMBR gap Equivalent unused space, So use one alonebios
boot Partition to allocate such space, To store complexboot loader.

BIOS
boot ZoningGUID Could be"21686148-6449-6E6F-744E-656564454649". On the basis ofBIOS Under the platform ofGPT in,BIOS
boot The partition is a bit likeEFI Under the platformEFI system partition,EFI System partition useUEFI Save file system and files, For useBIOS PlatformBIOS
boot Partition does not use file system to save code( See the picture above, staybios boot There is no file system created on the partition).

bios boot The size of the partition is very small, It can be as small as31kB( Because the first sector ismbr, thereforebios boot From the2 Sector to No.63 A sector), But because of the futureboot
loader May expand, So suggestbios
boot Partition set to1M Size, And many disk partitioning tools use1MB Partition alignment policy, suchMBR Some free space will be reserved between the first partition.



stayExample 2 in,grub 2 staybios boot Thecore.img.

 

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[ Translation and annotation1]gnu grub: Used nowgrub All aregnu It's from the strongholdgrub, Originalgrub Long gone in history.

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[ Translation and annotation2]: that isbios MBR andgpt Mixed mode.