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Instead of requiring that the BPB is always the FAT32 one, check the 

first three bytes to determine how much of the BPB to preserve.
Supported values:
	eb 3c 90        FAT16 BPB
	eb 58 90        FAT32 BPB
	(anything else)	don't preserve any BPB

This is because the BPB is generally only the FAT16 one except in the
bootxx_msdos case, where it's the larger FAT32 one.
This commit is contained in:
lukem 2003-10-14 09:46:43 +00:00
parent 3b192f5429
commit 10e10fae7e
1 changed files with 25 additions and 15 deletions
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40
usr.sbin/installboot/arch/i386.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: i386.c,v 1.10 2003/10/10 01:50:47 lukem Exp $ */
/* $NetBSD: i386.c,v 1.11 2003/10/14 09:46:43 lukem Exp $ */
/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
@ -38,7 +38,7 @@
#include <sys/cdefs.h>
#if defined(__RCSID) && !defined(__lint)
__RCSID("$NetBSD: i386.c,v 1.10 2003/10/10 01:50:47 lukem Exp $");
__RCSID("$NetBSD: i386.c,v 1.11 2003/10/14 09:46:43 lukem Exp $");
#endif /* __RCSID && !__lint */
#if HAVE_CONFIG_H
@ -61,8 +61,8 @@ __RCSID("$NetBSD: i386.c,v 1.10 2003/10/10 01:50:47 lukem Exp $");
int
i386_setboot(ib_params *params)
{
int retval, i;
char *bootstrapbuf;
int retval, i, bpbsize;
uint8_t *bootstrapbuf;
uint bootstrapsize;
ssize_t rv;
uint32_t magic;
@ -142,16 +142,22 @@ i386_setboot(ib_params *params)
}
/*
* Ensure bootxx hasn't got code (i.e, non-zero bytes) in
* the BIOS Parameter Block (BPB) or the partition table.
* Determine size of BIOS Parameter Block (BPB) to copy from
* original MBR to the temporary buffer by examining the first
* few instruction in the new bootblock. Supported values:
* eb 3c 90 jmp ENDOF(mbr_bpbFAT16)+1, nop
* eb 58 90 jmp ENDOF(mbr_bpbFAT32)+1, nop
* (anything else) ; don't preserve
*/
bpbsize = 0;
if (bootstrapbuf[0] == 0xeb && bootstrapbuf[2] == 0x90 &&
(bootstrapbuf[1] == 0x3c || bootstrapbuf[1] == 0x58))
bpbsize = bootstrapbuf[1] + 2 - MBR_BPB_OFFSET;
/*
* Ensure bootxx hasn't got any code or date (i.e, non-zero bytes) in
* the partition table.
*/
for (i = 0; i < sizeof(mbr.mbr_bpb); i++) {
if (*(uint8_t *)(bootstrapbuf + MBR_BPB_OFFSET + i) != 0) {
warnx("BPB has non-zero byte at offset %d in `%s'",
MBR_BPB_OFFSET + i, params->stage1);
goto done;
}
}
for (i = 0; i < sizeof(mbr.mbr_parts); i++) {
if (*(uint8_t *)(bootstrapbuf + MBR_PART_OFFSET + i) != 0) {
warnx(
@ -165,8 +171,12 @@ i386_setboot(ib_params *params)
* Copy the BPB and the partition table from the original MBR to the
* temporary buffer so that they're written back to the fs.
*/
memcpy(bootstrapbuf + MBR_BPB_OFFSET, &mbr.mbr_bpb,
sizeof(mbr.mbr_bpb));
if (bpbsize != 0) {
if (params->flags & IB_VERBOSE)
printf("Preserving %d (%#x) bytes of the BPB\n",
bpbsize, bpbsize);
memcpy(bootstrapbuf + MBR_BPB_OFFSET, &mbr.mbr_bpb, bpbsize);
}
memcpy(bootstrapbuf + MBR_PART_OFFSET, &mbr.mbr_parts,
sizeof(mbr.mbr_parts));