2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2011 Marius Strobl <marius@FreeBSD.org>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
33 #include <sys/systm.h>
36 #include <cam/cam_ccb.h>
38 #include <machine/md_var.h>
41 scsi_da_bios_params(struct ccb_calc_geometry *ccg)
43 uint32_t secs_per_cylinder, size_mb;
46 * The VTOC8 disk label only uses 16-bit fields for cylinders, heads
47 * and sectors so the geometry of large disks has to be adjusted.
48 * We generally use the sizing used by cam_calc_geometry(9), except
49 * when it would overflow the cylinders, in which case we use 255
50 * heads and sectors. This allows disks up to the 2TB limit of the
52 * XXX this doesn't match the sizing used by OpenSolaris, as that
53 * would exceed the 8-bit ccg->heads and ccg->secs_per_track.
55 if (ccg->block_size == 0)
57 size_mb = (1024L * 1024L) / ccg->block_size;
60 size_mb = ccg->volume_size / size_mb;
61 if (ccg->volume_size > (uint64_t)65535 * 255 * 63) {
63 ccg->secs_per_track = 255;
64 } else if (size_mb > 1024) {
66 ccg->secs_per_track = 63;
69 ccg->secs_per_track = 32;
71 secs_per_cylinder = ccg->heads * ccg->secs_per_track;
72 if (secs_per_cylinder == 0)
74 ccg->cylinders = ccg->volume_size / secs_per_cylinder;