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Diffstat (limited to 'contrib/syslinux/syslinux-4.03/doc/gpt.txt')
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diff --git a/contrib/syslinux/syslinux-4.03/doc/gpt.txt b/contrib/syslinux/syslinux-4.03/doc/gpt.txt deleted file mode 100644 index 0909932..0000000 --- a/contrib/syslinux/syslinux-4.03/doc/gpt.txt +++ /dev/null @@ -1,69 +0,0 @@ - GPT boot protocol - -There are two ways to boot a GPT-formatted disk on a BIOS system. -Hybrid booting, and the new GPT-only booting protocol originally -proposed by the author, and later adopted by the T13 committee in -slightly modified form. - - - *** Hybrid booting *** - -Hybrid booting uses a standard MBR, and has bootable ("active") -partitions present, as partitions, in the GPT PMBR sector. This means -the PMBR, instead of containing only one "protective" partition (type -EE), may contain up to three partitions: a protective partition (EE) -*before* the active partition, the active partition, and a protective -partition (EE) *after* the active partition. The active partition is -limited to the first 2^32 sectors (2 TB) of the disk. - -All partitions, including the active partition, should have GPT -partition entries. Thus, changing which partition is active does NOT -change the GPT partition table. - -This is the only known way to boot Microsoft operating systems from a -GPT disk with BIOS firmware. - - - *** New protocol *** - -This defines the T13-approved protocol for GPT partitions with BIOS -firmware. It maintains backwards compatibility to the extent -possible. It is implemented by the file mbr/gptmbr.bin. - -The (P)MBR format is the normal PMBR specified in the UEFI -documentation, with the first 440 bytes used for the boot code. The -partition to be booted is marked by setting bit 2 in the GPT Partition -Entry Attributes field (offset 48); this bit is reserved by the UEFI -Forum for "Legacy BIOS Bootable". - - - -> The handover protocol - -The PMBR boot code loads the first sector of the bootable partition, -and passes in DL=<disk number>, ES:DI=<pointer to $PnP>, sets EAX to -0x54504721 ("!GPT") and points DS:SI to a structure of the following -form: - - Offset Size Contents - --------------------------------------------------------- - 0 1 0x80 (this is a bootable partition) - 1 3 CHS of partition (using INT 13h geometry) - 4 1 0xED (partition type: synthetic) - 5 3 CHS of partition end - 8 4 Partition start LBA - 12 4 Partition end LBA - 16 4 Length of the GPT entry - 20 varies GPT partition entry - -The CHS information is optional; gptmbr.bin currently does *NOT* -calculate them, and just leaves them as zero. - -Bytes 0-15 matches the standard MBR handover (DS:SI points to the -partition entry), except that the information is provided -synthetically. The MBR-compatible fields are directly usable if they -are < 2 TB, otherwise these fields should contain 0xFFFFFFFF and the -OS will need to understand the GPT partition entry which follows the -MBR one. The "!GPT" magic number in EAX and the 0xED partition type -also informs the OS that the GPT partition information is present. - -Syslinux 4.00 and later fully implements this protocol. |