Changeset 67694 in vbox for trunk/src/VBox/Devices/PC

Timestamp:

Jun 29, 2017 12:38:16 PM (8 years ago)

Author:

vboxsync

Message:

BIOS: INT 13h, INT 15h always returns with interrupts enabled.

Location:

trunk/src/VBox/Devices/PC/BIOS

Files:

• disk.c (modified) (1 diff)
• floppy.c (modified) (1 diff)
• notes.txt (modified) (1 diff)
• orgs.asm (modified) (2 diffs)

trunk/src/VBox/Devices/PC/BIOS/disk.c

@@ -132 +132 @@
 
     BX_DEBUG_INT13_HD("%s: AX=%04x BX=%04x CX=%04x DX=%04x ES=%04x\n", __func__, AX, BX, CX, DX, ES);
+
+    SET_IF();   /* INT 13h always returns with interrupts enabled. */
 
     bios_dsk = read_word(0x0040,0x000E) :> &EbdaData->bdisk;

trunk/src/VBox/Devices/PC/BIOS/floppy.c

@@ -474 +474 @@
     BX_DEBUG_INT13_FL("%s: AX=%04x BX=%04x CX=%04x DX=%04x ES=%04x\n", __func__, AX, BX, CX, DX, ES);
 
+    SET_IF();   /* INT 13h always returns with interrupts enabled. */
+
     switch ( GET_AH() ) {
     case 0x00: // diskette controller reset

trunk/src/VBox/Devices/PC/BIOS/notes.txt

@@ -14 +14 @@
 - Keystroke check (INT 16h, fn 01h/10h) always enables interrupts on return.
   DOS POWER.EXE depends on that in some situations.
+
+- MS-DOS 5.0/V setup assumes that INT 13h always returns with interrupts
+  enabled.
+
+- INT 15h also always returns with interrupts enabled (even for unsupported
+  functions).
 
 - MS-DOS 6.2/V is a rare user of the INT 15h keyboard intercept routines.

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

@@ -1764 +1764 @@
                 mov     bp, sp
                 and     byte ptr [bp + 6], 0FEh
+                or      word ptr [bp + 6], 0200h
                 pop     bp
                 iret
@@ -1769 +1770 @@
                 push    bp
                 mov     bp, sp
-                or      byte ptr [bp + 6], 1
+                or      word ptr [bp + 6], 0201h
                 pop     bp
                 iret