[src/trunk]: src/sys/arch/i386/stand/bootxx Remove home grown GPT MBR handoff...

[jakllsch <jakllsch%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/47704414806b
branches:  trunk
changeset: 768443:47704414806b
user:      jakllsch <jakllsch%NetBSD.org@localhost>
date:      Wed Aug 17 00:07:38 2011 +0000

description:
Remove home grown GPT MBR handoff support in favor of T13 EDD-4 annex A,
which does the same thing in a more interoperable way.

diffstat:

 sys/arch/i386/stand/bootxx/pbr.S |  36 ++++++++++++++++++------------------
 1 files changed, 18 insertions(+), 18 deletions(-)

diffs (74 lines):

diff -r d2dea1cecb02 -r 47704414806b sys/arch/i386/stand/bootxx/pbr.S
--- a/sys/arch/i386/stand/bootxx/pbr.S  Wed Aug 17 00:04:41 2011 +0000
+++ b/sys/arch/i386/stand/bootxx/pbr.S  Wed Aug 17 00:07:38 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pbr.S,v 1.19 2011/01/06 01:08:48 jakllsch Exp $        */
+/*     $NetBSD: pbr.S,v 1.20 2011/08/17 00:07:38 jakllsch Exp $        */
 
 /*-
  * Copyright (c) 2003,2004 The NetBSD Foundation, Inc.
@@ -97,8 +97,9 @@
  * sector we were loaded from (if we were loaded by NetBSD mbr code).
  * In any case we have to re-read sector zero of the disk and hunt
  * through the BIOS partition table for the NetBSD partition.
- * However, if there's a magic number in %eax, then %ecx:%ebx
- * contains the sector we were loaded from.
+ *
+ * Or, we may have been loaded by a GPT hybrid MBR, handoff state is
+ * specified in T13 EDD-4 annex A.
  */
 
        .text
@@ -121,19 +122,16 @@
 
        . = start + MBR_AFTERBPB        /* skip BPB */
 start0:
+       xor     %cx, %cx                /* don't trust values of ds, es or ss */
+       mov     %cx, %ss
+       mov     %cx, %sp
+       mov     %cx, %es
 #ifndef BOOT_FROM_FAT
-       movl    %eax, %edi              /* move %eax magic out of the way */
-#endif
-       xor     %ax, %ax                /* don't trust values of ds, es or ss */
-       mov     %ax, %ds
-       mov     %ax, %es
-       mov     %ax, %ss
-       mov     $0xfffc, %sp
-
-#ifndef BOOT_FROM_FAT
-       cmpl    $X86_MBR_GPT_MAGIC, %edi /* did mbr_gpt leave us a LBA? */
+       cmpl    $0x54504721, %eax       /* did a GPT hybrid MBR start us? */
        je      boot_gpt
 #endif
+       mov     %cx, %ds
+       xor     %ax, %ax
 
        /* A 'reset disk system' request is traditional here... */
        push    %dx                     /* some BIOS zap %dl here :-( */
@@ -141,7 +139,7 @@
        pop     %dx
 
        /* Read from start of disk */
-       movw    $0x0001, %cx            /* track zero sector 1 */
+       incw    %cx                     /* track zero sector 1 */
        movb    %ch, %dh                /* dh = head = 0 */
        call    chs_read
 
@@ -368,10 +366,12 @@
 
 #ifndef BOOT_FROM_FAT
 boot_gpt:
-       /* 64-bit LBA in %ecx:%ebx */
-       movl    %ebx, lba_sector
-       movl    %ecx, lba_sector + 4
-       movl    %ebx, %ebp
+       movl    (20+32+0)(%si), %ebp
+       movl    (20+32+4)(%si), %edi
+       movw    %cx, %ds
+       movl    %ebp, lba_sector + 0
+       movl    %edi, lba_sector + 4
+       movl    %ebp, %esi
        jmp     boot_lba
 #endif