diff options
Diffstat (limited to 'sys/arch/i386/stand/libsa/real_prot.S')
| -rw-r--r-- | sys/arch/i386/stand/libsa/real_prot.S | 45 |
1 files changed, 17 insertions, 28 deletions
diff --git a/sys/arch/i386/stand/libsa/real_prot.S b/sys/arch/i386/stand/libsa/real_prot.S index 765c318cc76..ff7b4beaa6d 100644 --- a/sys/arch/i386/stand/libsa/real_prot.S +++ b/sys/arch/i386/stand/libsa/real_prot.S @@ -1,4 +1,4 @@ -/* $OpenBSD: real_prot.S,v 1.2 1997/03/31 03:12:16 weingart Exp $ */ +/* $OpenBSD: real_prot.S,v 1.3 1997/03/31 23:06:31 mickey Exp $ */ /* * Mach Operating System @@ -26,7 +26,6 @@ * the rights to redistribute these changes. * * from: Mach, Revision 2.2 92/04/04 11:34:13 rpd - * $Id: real_prot.S,v 1.2 1997/03/31 03:12:16 weingart Exp $ */ @@ -77,9 +76,8 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * transfer from real mode to protected mode. */ -.align 4,0x90 ENTRY(real_to_prot) - /* guarantee that interrupt is disabled when in prot mode */ + /* guarantee that interrupts are disabled when in prot mode */ cli /* load the gdtr */ @@ -108,6 +106,8 @@ ENTRY(real_to_prot) movl %ax, %ds movl %ax, %ss movl %ax, %es + movl %ax, %fs + movl %ax, %gs #ifndef NO_IDTR /* load idtr so we can debug */ @@ -122,44 +122,33 @@ ENTRY(real_to_prot) * */ -.align 4,0x90 ENTRY(prot_to_real) - /* - * This is self-modifying code, but we need a writable - * code segment, and an intersegment return does not give us that. - */ - movw _codeseg, %ax - pushw %ax - movw $2f, %ax - pushw %ax + movl _codeseg, %eax + # movw %ax, 2f /* Change to use16 mode. */ ljmp $0x18, $1f - -1: /* clear the PE bit of CR0 */ +1: + /* clear the PE bit of CR0 */ movl %cr0, %eax data32 andl $~CR0_PE, %eax movl %eax, %cr0 - /* - * make intersegment jmp to flush the processor pipeline - * using the fake stack frame set up earlier - * and reload CS register - */ -#if 0 - hlt -#endif - lret -2: /* - * we are in real mode now - * set up the real mode segment registers : DS, SS, ES - */ + data32 + # ljmp _codeseg, $2f + .byte 0xea + .long 3f +2: .word 0 +3: + /* setup: %ds, %es, %ss */ movl %cs, %ax movl %ax, %ds movl %ax, %ss movl %ax, %es + movl %ax, %fs + movl %ax, %gs #ifndef NO_IDTR /* load idtr so we can debug */ addr32 |