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

diff --git a/DuetPkg/BootSector/bootsect.asm b/DuetPkg/BootSector/bootsect.asm
index 8fb7236bc1793f9f9f30c12a05d2ec56ffbae4e1..1b8c15bc80eb47ac4e5bcc5f5307875e62fc1b77 100644 (file)
--- 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,                     \r
 ;*   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             \r
 ;*   \r
-;*    bootsect.asm\r
-;*  \r
-;*   Abstract:\r
+;*   bootsect.asm\r
+;*    \r
+;*   bootsect.asm is built as 16-bit binary file in 512 bytes and patched to disk/partition's \r
+;*   first section - boot sector. \r
+;*\r
+;*   The startup sequence for DUET disk boot sector is:\r
+;*\r
+;*   1, LegacyBios check 0xAA55 signature at boot sectore offset 0x1FE to judget \r
+;*      whether disk/partition is bootable.\r
+;*   2, LegacyBios will load boot sector to 0x7c00 in real mode, pass BPB data and\r
+;*      hand off control to 0x7c00 code.\r
+;*   3, boot sector code simply parse FAT format in boot disk and find EfiLdr binary file \r
+;*      and EfiVar.bin if exists. For first boot, EfiVar.bin does not exist.\r
+;*   4, boot sector load the first sector of EfiLdr binary which is start.com to\r
+;*      0x2000:0x0000 address.\r
+;*   5, boot sector handoff control to 0x2000:0x0000 for start.com binary.\r
 ;*\r
 ;------------------------------------------------------------------------------\r
 \r