diff options
| -rw-r--r-- | sys/i386/boot/biosboot/start.S | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/sys/i386/boot/biosboot/start.S b/sys/i386/boot/biosboot/start.S index d0bcbf89859a..a30ab6804f2e 100644 --- a/sys/i386/boot/biosboot/start.S +++ b/sys/i386/boot/biosboot/start.S @@ -24,7 +24,7 @@ * the rights to redistribute these changes. * * from: Mach, Revision 2.2 92/04/04 11:36:29 rpd - * $Id: start.S,v 1.4 1994/10/02 05:18:26 rgrimes Exp $ + * $Id: start.S,v 1.5 1994/10/06 09:41:05 rgrimes Exp $ */ /* @@ -51,7 +51,7 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include "asm.h" - .file "start.s" + .file "start.S" SIGNATURE= 0xaa55 LOADSZ= 15 /* size of unix boot */ @@ -99,7 +99,14 @@ start: jae hd fd: + /* + * XXX some bootstraps don't pass the drive number in %dl. + * This is a problem mainly when we are block 0 on a floppy. + * Force drive 0 for floppies. + * XXX %dl was assumed valid in the test that led here. + */ mov $0x0, %dl + /* reset the disk system */ #ifdef DEBUG data32 @@ -274,7 +281,14 @@ seven: String "7\r\n\0" eread: String "Read error\r\n\0" enoboot: String "No bootable partition\r\n\0" endofcode: -/* throw in a partition in case we are block0 as well */ +/* + * Dummy partition table in case we are block 0. The ending c/h/s values + * of the non-null partition are almost arbitary. The length of this + * partition is bogus for backwards compatibility and as a signature. + * A real partition table shouldn't be as weird and broken as this one, + * and the isa slice initialization routine interprets this table as + * saying that the whole disk is used for FreeBSD. + */ /* flag, head, sec, cyl, typ, ehead, esect, ecyl, start, len */ . = EXT(boot1) + PARTSTART .byte 0x0,0,0,0,0,0,0,0 |