Changeset 67115 in vbox for trunk/src/VBox/Devices/PC/BIOS

Timestamp:

May 26, 2017 11:52:06 AM (8 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

115782

Message:

BIOS: Clear high bits of registers after POST.

Location:

trunk/src/VBox/Devices/PC/BIOS

Files:

• makefile (modified) (1 diff)
• orgs.asm (modified) (1 diff)

trunk/src/VBox/Devices/PC/BIOS/makefile

@@ -21 +21 @@
 
 DEFS = -DVBOX -DVBOX_LANBOOT_SEG=0xE200 -DVBOX_VERSION_STRING=$(Q)0.9$(Q) &
- -DVBOX_WITH_SCSI -DVBOX_BIOS_CPU=80286
+ -DVBOX_WITH_SCSI -DVBOX_BIOS_CPU=80386
 
 AFLAGS = -q -0 -wx

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

@@ -638 +638 @@
                 call    rom_scan_
                 
+if VBOX_BIOS_CPU ge 80386
+                ;; The POST code does not bother preserving high bits of the
+                ;; 32-bit registers. Now is a good time to clear them so that
+                ;; there's no garbage left in high bits.
+                .386
+                xor     eax, eax
+                xor     ebx, ebx
+                xor     ecx, ecx
+                xor     edx, edx
+                .286
+endif
+
                 call    _print_bios_banner