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Add comments for introducing startup sequence for DUET boot disk.

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git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@8043 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
klu2 2009-04-09 06:19:15 +00:00
parent c0e741ef23
commit 8141eea5fa
1 changed files with 15 additions and 3 deletions
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18
DuetPkg/BootSector/bootsect.S
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@ -9,13 +9,25 @@
#* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
#* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#*
#* bootsect.asm
#* bootsect.S
#*
#* Abstract:
#* bootsect.S is built as 16-bit binary file in 512 bytes and patched to disk/partition's
#* first section - boot sector.
#*
#* The startup sequence for DUET disk boot sector is:
#*
#* 1, LegacyBios check 0xAA55 signature at boot sectore offset 0x1FE to judget
#* whether disk/partition is bootable.
#* 2, LegacyBios will load boot sector to 0x7c00 in real mode, pass BPB data and
#* hand off control to 0x7c00 code.
#* 3, boot sector code simply parse FAT format in boot disk and find EfiLdr binary file
#* and EfiVar.bin if exists. For first boot, EfiVar.bin does not exist.
#* 4, boot sector load the first sector of EfiLdr binary which is start.com to
#* 0x2000:0x0000 address.
#* 5, boot sector handoff control to 0x2000:0x0000 for start.com binary.
#*
#------------------------------------------------------------------------------
#.MODEL small
.stack:
.486p:
.code16