From c0e741ef23ed1091af6215699c940e71079ce6ae Mon Sep 17 00:00:00 2001 From: klu2 Date: Thu, 9 Apr 2009 06:16:52 +0000 Subject: [PATCH] Add comments for introducing startup sequence for DUET boot disk. git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@8042 6f19259b-4bc3-4df7-8a09-765794883524 --- DuetPkg/BootSector/bootsect.asm | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/DuetPkg/BootSector/bootsect.asm b/DuetPkg/BootSector/bootsect.asm index 8fb7236bc1..1b8c15bc80 100644 --- a/DuetPkg/BootSector/bootsect.asm +++ b/DuetPkg/BootSector/bootsect.asm @@ -9,9 +9,22 @@ ;* 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 -;* -;* Abstract: +;* bootsect.asm +;* +;* bootsect.asm 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. ;* ;------------------------------------------------------------------------------ -- 2.39.2