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git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7816 6f19259b-4bc3-4df7-8a09-765794883524

diff --git a/DuetPkg/BootSector/bootsect.asm b/DuetPkg/BootSector/bootsect.asm
index 972e36e8a1666fd140ea491c3ecb4c024954d437..8fb7236bc1793f9f9f30c12a05d2ec56ffbae4e1 100644 (file)
--- a/DuetPkg/BootSector/bootsect.asm
+++ b/DuetPkg/BootSector/bootsect.asm
@@ -81,13 +81,13 @@ BootSectorEntryPoint:
   mov   ah,8                                ; ah = 8 - Get Drive Parameters Function\r
   mov   byte ptr [bp+PhysicalDrive],dl      ; BBS defines that BIOS would pass the booting driver number to the loader through DL\r
   int   13h                                 ; Get Drive Parameters\r
-  xor   ax,ax                   ; ax = 0\r
-  mov   al,dh                   ; al = dh\r
-  inc   al                      ; MaxHead = al + 1\r
-  push  ax                      ; 0000:7bfe = MaxHead\r
-  mov   al,cl                   ; al = cl\r
-  and   al,03fh                 ; MaxSector = al & 0x3f\r
-  push  ax                      ; 0000:7bfc = MaxSector\r
+  xor   ax,ax                               ; ax = 0\r
+  mov   al,dh                               ; al = dh (number of sides (0 based))\r
+  inc   al                                  ; MaxHead = al + 1\r
+  push  ax                                  ; 0000:7bfe = MaxHead\r
+  mov   al,cl                               ; al = cl (CL = sectors per track)\r
+  and   al,03fh                             ; MaxSector = al & 0x3f\r
+  push  ax                                  ; 0000:7bfc = MaxSector\r
 \r
   cmp   word ptr [bp+SectorSignature],0aa55h  ; Verify Boot Sector Signature\r
   jne   BadBootSector\r
@@ -149,7 +149,7 @@ FindNext:
   jmp   NotFoundAll\r
 \r
 FoundAll:\r
-FoundEFILDR:\r
+FoundEFILDR:                                  ; 0x7cfe\r
   mov     cx,bx                               ; cx = Start Cluster for EFILDR  <----------------------------------\r
   mov     ax,cs                               ; Destination = 2000:0000\r
   add     ax,2000h\r
@@ -170,8 +170,8 @@ ReadFirstClusterOfEFILDR:
   call    ReadBlocks\r
   pop     ax\r
 JumpIntoFirstSectorOfEFILDR:\r
-  mov     word ptr [bp+JumpSegment],ax\r
-JumpFarInstruction:\r
+  mov     word ptr [bp+JumpSegment],ax        ; 0x7d26\r
+JumpFarInstruction:                           ; 0x7d2a\r
   db      0eah\r
 JumpOffset:\r
   dw      0000h\r
@@ -252,7 +252,7 @@ LimitTransfer:
 ; ****************************************************************************\r
 ; ERROR Condition:\r
 ; ****************************************************************************\r
-NotFoundAll:\r
+NotFoundAll:                            ; 0x7da6\r
   ; if we found EFILDR, continue\r
   test bx,bx\r
   jne  FoundEFILDR\r