[src/trunk]: src/sys/arch/i386/stand/mbr Make mbr_bootsel boot active partiti...

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

details:   https://anonhg.NetBSD.org/src/rev/8b272be408f1
branches:  trunk
changeset: 566419:8b272be408f1
user:      dsl <dsl%NetBSD.org@localhost>
date:      Sat May 08 21:18:22 2004 +0000

description:
Make mbr_bootsel boot active partition if/when no menu items are output.
Stops users sitting in front of a system that is waiting for a keypress.
Just don't ask how I added more functionality AND got an extra 7 free bytes!

diffstat:

 sys/arch/i386/stand/mbr/mbr.S |  85 +++++++++++++++++++++++-------------------
 1 files changed, 46 insertions(+), 39 deletions(-)

diffs (175 lines):

diff -r a96f91b8f3de -r 8b272be408f1 sys/arch/i386/stand/mbr/mbr.S
--- a/sys/arch/i386/stand/mbr/mbr.S     Sat May 08 21:05:02 2004 +0000
+++ b/sys/arch/i386/stand/mbr/mbr.S     Sat May 08 21:18:22 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: mbr.S,v 1.6 2004/04/23 06:21:21 dsl Exp $      */
+/*     $NetBSD: mbr.S,v 1.7 2004/05/08 21:18:22 dsl Exp $      */
 
 /*
  * Copyright (c) 1999-2004 The NetBSD Foundation, Inc. 
@@ -49,6 +49,11 @@
  * NO_LBA_CHECK        - no check if bios supports LBA reads
  */
 
+#ifdef BOOT_EXTENDED
+#define NO_CHS 1
+#define BOOTSEL        1
+#endif
+
 #include <machine/asm.h>
 #include <sys/bootblock.h>
 
@@ -120,7 +125,6 @@
        push    %dx                     /* save drive number */
        push    %dx                     /* twice - for err_msg loop */
 
-#ifdef BOOTSEL
 /*
  * Walk through the selector (name) table printing used entries.
  */
@@ -134,8 +138,9 @@
        lea     parttab - nametab(%bx), %bp
 next_ptn:
        movb    4(%bp), %al             /* partition type */
+#ifdef NO_CHS
+       movl    8(%bp), %edi            /* partition sector number */
 #ifdef BOOT_EXTENDED
-       movl    8(%bp), %edi            /* partition sector number */
        cmpb    $MBR_PTYPE_EXT, %al     /* Extended partition */
        je      1f
        cmpb    $MBR_PTYPE_EXT_LBA, %al /* Extended LBA partition */
@@ -143,14 +148,26 @@
        cmpb    $MBR_PTYPE_EXT_LNX, %al /* Linux extended partition */
        jne     2f
 1:     movl    %edi, %edx              /* save next extended ptn */
-       jmp     3f
+       jmp     4f
 2:
 #endif
+       addl    lba_sector, %edi        /* add in extended ptn base */
+#endif
        test    %al, %al                /* undefined partition */
-       je      3f
+       je      4f
+       cmpb    $0x80, (%bp)            /* check for active partition */
+       jne     3f                      /* jump if not... */
+#define        ENTER   (4 * ((SCAN_ENTER - SCAN_F1) & 0xff))
+#ifdef NO_CHS
+       movl    %edi, ptn_list + ENTER  /* save location of active ptn */
+#else
+       mov     %bp, ptn_list + ENTER
+#endif
+#undef ENTER
+3:
+#ifdef BOOTSEL
        cmpb    $0, (%bx)               /* check for prompt */
-       jz      3f
-
+       jz      4f
        /* output menu item */
        movw    $prefix, %si
        incb    (%si)
@@ -159,7 +176,6 @@
        shl     $2, %si                 /* const + count * 4 */
 #define        CONST   (4 * ((':' << 8) + '1' - ((SCAN_1 - SCAN_F1) & 0xff)))
 #ifdef NO_CHS
-       addl    lba_sector, %edi
        movl    %edi, ptn_list - CONST(%si)     /* sector to read */
 #else
        mov     %bp, ptn_list - CONST(%si)      /* partition info */
@@ -169,7 +185,8 @@
        call    message                 /* prompt */
        movw    $crlf, %si
        call    message
-3:
+#endif
+4:
        add     $0x10, %bp
        add     $TABENTRYSIZE, %bx
        cmpb    $(nametab - start - 0x100) + 4 * TABENTRYSIZE, %bl
@@ -198,6 +215,21 @@
 #endif
 
 /*
+ * If we haven't output any menu entries, then the system sits waiting
+ * for a keypress with the user looking at a blank screen wondering
+ * why nothing is happening.
+ * To stop this we generate <ENTER> - to boot the active partition
+ * if we haven't output any menu texts.
+ * The non-bootsel code also traverses this code path.
+ */
+
+#ifndef BOOTSEL
+       movb    $SCAN_ENTER - SCAN_F1, %al
+#else
+       movb    $SCAN_ENTER, %al        /* default to active partition */
+       cmpb    $'0', prefix            /* did we output a menu ? */
+       je      check_key               /* Nope - process SCAN_ENTER */
+/*
  * Get the initial time value for the timeout comparison. It is returned
  * by int 1a in cx:dx. We do sums modulo 2^16 so it doesn't matter if
  * the counter wraps (which it does every hour) - so we can safely
@@ -234,41 +266,12 @@
  */
 check_key:
 /*
- * <enter> -> boot active partition.
- */
-       cmpb    $SCAN_ENTER, %al
-       jne     boot_disk
-#endif /* BOOTSEL */
-
-/*
- * Scan MBR for first active partition, and boot it.
- */
-       mov     $MBR_PART_COUNT, %cx
-       mov     $parttab, %si
-1:
-       cmpb    $0x80, (%si)
-#ifdef NO_CHS
-       jne     10f                     /* not active */
-       movl    8(%si), %ebp            /* sector number of ptn */
-       jmp     boot_lba
-10:
-#else
-       je      boot_si
-#endif
-       add     $0x10, %si
-       loop    1b
-       set_err(ERR_INVPART)
-       jmp     err_msg
-
-#ifdef BOOTSEL
-/*
  * F1-F10 -> boot disk 0-9. Check if the requested disk isn't above
  * the number of disks actually in the system as stored in 0:0475 by
  * the BIOS.
  * If we trust loc 475, we needn't check the upper bound on the keystroke
  * This is always sector 0, so always read using chs.
  */
-boot_disk:
        subb    $SCAN_F1, %al
        cmpb    0x0475, %al
        jae     boot_ptn
@@ -282,6 +285,7 @@
        movw    $chs_zero, %si          /* chs read sector zero info */
        jmp     read_chs
 #endif
+#endif /* BOOTSEL */
 
 /*
  * Boot requested partition.
@@ -303,9 +307,12 @@
        test    %si, %si
        jnz     boot_si
 #endif
+#ifdef BOOTSEL
        set_err(ERR_KEY)
+#else
+       set_err(ERR_INVPART)
+#endif
   /*   jmp     err_msg */
-#endif /* BOOTSEL */
 
 /* Something went wrong...
  * Output error code,