Changeset 1118 in vbox for trunk/src/VBox/Devices/PC/Etherboot-src/arch/i386

Timestamp:

Feb 28, 2007 4:42:54 PM (18 years ago)

Author:

vboxsync

Message:

Detect attempt to enter PXE code in V86 mode. Print error message and
send guest into a tight hlt loop.

File:

• trunk/src/VBox/Devices/PC/Etherboot-src/arch/i386/core/realmode_asm.S (modified) (1 diff)

trunk/src/VBox/Devices/PC/Etherboot-src/arch/i386/core/realmode_asm.S

@@ -934 +934 @@
     popfl
 #endif /* VBOX_DEBUG_PXE_EP */
+#ifdef VBOX
+        /* Detect V86 mode. Etherboot doesn't work in V86 mode, because it
+         * switches to protected mode on entry. The follow-up project gPXE
+         * can run completely in real mode (and thus can implement the full
+         * PXE calling conventions), but its PXE support isn't anywhere near
+         * what Etherboot currently provides. */
+        pushw %ax
+        smsw %ax
+        andw $0x0001,%ax
+        jz 4f
+        push %cs
+        pop %ds
+        call 0f
+0:      popw %si
+        addl $msg_v86_unsupported-0b,%si    /* start of zero-terminated string */
+1:
+        cld
+        lodsb
+        or %al,%al
+        jnz 3f
+
+2:      hlt
+        jmp 2b
+
+msg_v86_unsupported: .asciz "\r\nVirtualBox PXE cannot be used from V86 mode. Guest halted.\r\n"
+
+3:
+        mov $0x0e,%ah   /* teletype output character at cursor position */
+        mov $0x0070,%bx /* page 0, attribute 0x70 */
+        int $0x10
+        jmp 1b
+4:
+        popw %ax
+#endif /* VBOX */
         /* Perform real-mode in_call */
         call    pxe_rm_in_call