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Add a way to force (at compile time) use of int13 extensions.

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This commit is contained in:
thorpej 2003-06-25 04:21:51 +00:00
parent daf8a4ad8e
commit 7401047528
1 changed files with 21 additions and 2 deletions
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23
sys/arch/i386/stand/lib/biosdisk_ll.c
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@ -1,4 +1,4 @@
/* $NetBSD: biosdisk_ll.c,v 1.17 2003/04/16 12:41:03 dsl Exp $ */
/* $NetBSD: biosdisk_ll.c,v 1.18 2003/06/25 04:21:51 thorpej Exp $ */
/*
* Copyright (c) 1996
@ -116,6 +116,25 @@ static int ra_dev;
static int ra_end;
static int ra_first;
/*
* Because some older BIOSes have bugs in their int13 extensions, we
* only try to use the extended read if the I/O request can't be addressed
* using CHS.
*
* Of course, some BIOSes have bugs in ths CHS read, such as failing to
* function properly if the MBR table has a different geometry than the
* BIOS would generate internally for the device in question, and so we
* provide a way to force the extended on hard disks via a compile-time
* option.
*/
#if defined(FORCE_INT13EXT)
#define NEED_INT13EXT(d, dblk, num) \
(((d)->dev & 0x80) != 0)
#else
#define NEED_INT13EXT(d, dblk, num) \
(((d)->dev & 0x80) != 0 && ((dblk) + (num)) >= (d)->chs_sectors)
#endif
static int
do_read(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf)
{
@ -129,7 +148,7 @@ do_read(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf)
int64_t sec;
} ext;
if ((d->dev & 0x80) && (dblk + num) >= d->chs_sectors) {
if (NEED_INT13EXT(d, dblk, num)) {
if (!(d->flags & BIOSDISK_EXT13))
return -1;
ext.size = sizeof(ext);