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pc86: add degenerate "hard disk partition table" to boot sector

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This is needed on some PCs to boot the pc86.img as a USB drive.
This commit is contained in:
tkchia 2022-09-20 16:14:38 +00:00
parent 8619ce3ada
commit b59422a24b
1 changed files with 16 additions and 1 deletions
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17
plat/pc86/boot.s
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@ -302,8 +302,23 @@ argv: .data2 exename, 0
envp: .data2 0 envp: .data2 0
exename: .asciz 'pc86.img' exename: .asciz 'pc86.img'
! A degenerate "hard disk partition table" covering this boot
! sector (possibly needed if booting from a USB drive).
.seek 0x1BE
.data1 0x80 ! boot indicator (0x80 = active)
.data1 0x00 ! partition start head
.data1 0x01 ! partition start sector and start track high
.data1 0x00 ! partition start track low
.data1 0x7F ! OS or filesystem indicator
.data1 0xFF ! partition end head
.data1 0xFF ! partition end sector and end track high
.data1 0xFF ! partition end track low
.data4 0 ! partition start LBA
.data4 0xFFFFFFFF ! length of partition in sectors
! ...and we need this to fool the PC into booting our boot sector. ! ...and we need this to fool the PC into booting our boot sector.
.seek 0x1FE .seek 0x1FE
.data2 0xAA55 .data2 0xAA55