Remove "force CHS" remnants. LBA uber alles.

Mildly sad noises from Nick.

ok miod@ mlarkin@

diff --git a/sys/arch/amd64/stand/biosboot/biosboot.S b/sys/arch/amd64/stand/biosboot/biosboot.S
index 294388a..4ec41e1 100644 (file)
--- a/sys/arch/amd64/stand/biosboot/biosboot.S
+++ b/sys/arch/amd64/stand/biosboot/biosboot.S
@@ -1,4 +1,4 @@
-/*     $OpenBSD: biosboot.S,v 1.10 2020/03/09 06:16:56 otto Exp $      */
+/*     $OpenBSD: biosboot.S,v 1.11 2022/08/31 09:20:57 krw Exp $       */
 
 /*
  * Copyright (c) 2003 Tobias Weingartner
@@ -114,17 +114,10 @@
  *
  * All of these are patched directly into the code where they are used
  * (once only, each), to save space.
- *
- * One more symbol is exported, in anticipation of a "-c" flag in
- * installboot to force CHS reads:
- *
- * force_chs   uint8   set to the value 1 to force biosboot to use CHS
- *                     reads (this will of course cause the boot sequence
- *                     to fail if /boot is above 8 GB).
  */
 
        .globl  inodeblk, inodedbl, fs_bsize_p, fsbtodb, p_offset, nblocks
-       .globl  fs_bsize_s, force_chs, blkincr
+       .globl  fs_bsize_s, blkincr
        .type   inodeblk, @function
        .type   inodedbl, @function
        .type   fs_bsize_p, @function
@@ -132,7 +125,6 @@
        .type   fsbtodb, @function
        .type   p_offset, @function
        .type   nblocks, @function
-       .type   force_chs, @function
        .type   blkincr, @function
 
 
@@ -240,56 +232,17 @@ main:
        /*
         * We're going to print our sign-on message.
         *
-        * We're now LBA-aware, and will use LBA to load /boot if the
-        * BIOS says it's available.  However, we have seen machines
-        * where CHS is required even when LBA is available.  Therefore
-        * we provide a way to force CHS use:
-        *
-        * If the SHIFT key is held down on entry, force CHS reads.
-        */
-       movw    $load_msg+1, %si        /* "Loading" */
-       movb    %dl, %dh
-
-       /*
-        * BIOS call "INT 0x16 Get Keyboard Shift Flags
-        *      Call with       %ah = 0x02
-        *      Return:
-        *                      %al = shift flags
-        *                      %ah - undefined by many BIOSes
-        */
-       movb    $0x02, %ah
-       int     $0x16
-
-       /*
-        * We provide the ability to force CHS use without having to hold
-        * down the SHIFT key each boot.  Just set the byte at force_chs
-        * to 1 (more accurately any value with either of the bottom two
-        * bits set, but the use of 1 is recommended).
+        * We're now LBA-aware, and will use LBA to load /boot if
+     * it's available.
         */
-force_chs = .+1
-       orb     $0, %al
-
-       testb   $0x3, %al               /* Either shift key down? */
-       jz      no_force_chs
-
-       decw    %si                     /* "!Loading" indicates forced CHS */
-       xorb    %dh, %dh                /* Pretend a floppy, so no LBA use */
-
-no_force_chs:
-       /* Print pretty message */
-       call    Lmessage
+       movw    $load_msg, %si  /* "Loading" */
+       call    Lmessage /* Print pretty message */
 
        /*
-        * We will use LBA reads if we have LBA support, so find out.
-        */
-
-       /*
-        * But don't even try on floppies, OR if forcing to CHS.
-        *
-        * (We're really testing %dl, but use %dh so we can force the
-        * top bit to zero to force CHS boot.)
+        * We will use LBA reads if we have LBA support, but don't even try
+     * on floppies.
         */
-       testb   $0x80, %dh
+       testb   $0x80, %dl
        jz      no_lba
 
        /*
@@ -895,7 +848,7 @@ lba_sector:
        .long   0, 0                    /* sector number */
 
 load_msg:
-       .asciz  "!Loading"
+       .asciz  "Loading"
 err_txt_crlf:
        .ascii  "\r\n"
 err_txt: