Changeset 44107 in vbox for trunk/src/VBox/Devices/PC

Timestamp:

Dec 12, 2012 2:10:08 PM (12 years ago)

Author:

vboxsync

Message:

BIOS: Reset CPU if POST entered in V86 mode.

File:

• trunk/src/VBox/Devices/PC/BIOS/orgs.asm (modified) (3 diffs)

trunk/src/VBox/Devices/PC/BIOS/orgs.asm

@@ -215 +215 @@
                 ret
 
+                ;; routine to write the pointer in DX:AX to memory starting
+                ;; at DS:BX (repeat CX times)
+                ;; - modifies BX, CX
+set_int_vects   proc    near
+
+                mov     [bx], ax
+                mov     [bx+2], dx
+                add     bx, 4
+                loop    set_int_vects
+                ret
+
+set_int_vects   endp
+
 ;; --------------------------------------------------------
 ;; POST entry point
@@ -220 +233 @@
                 BIOSORG 0E05Bh
 post:
+                cli
+
+                ;; Check if in protected (V86) mode. If so, the CPU needs
+                ;; to be reset.
+                smsw    ax
+                test    ax, 1
+                jz      in_real_mode
+
+                ;; Reset processor to get out of protected mode. Use system
+                ;; port instead of KBC.
+                ;; NB: We only need bit 0 to be set in AL, which we just
+                ;; determined to be the case.
+                out     92h, al
+                jmp     $               ; not strictly necessary in a VM
+                
+                
+in_real_mode:
+                ;; TODO: This looks very iffy - we shouldn't mess with any
+                ;; hardware until after we've established that cold boot
+                ;; needs to be done.
+                
                 xor     ax, ax
 
@@ -263 +297 @@
                 jmp     normal_post
 
-
-                ;; routine to write the pointer in DX:AX to memory starting
-                ;; at DS:BX (repeat CX times)
-                ;; - modifies BX, CX
-set_int_vects   proc    near
-
-                mov     [bx], ax
-                mov     [bx+2], dx
-                add     bx, 4
-                loop    set_int_vects
-                ret
-
-set_int_vects   endp
-
 normal_post:
                 ;; shutdown code 0: normal startup
-                cli
+
                 ;; Set up the stack top at 0:7800h. The stack should not be
                 ;; located above 0:7C00h; that conflicts with PXE, which