The Sun disk label only uses 16-bit fields for cylinders, heads and

sectors so the geometry of large IDE disks has to be adjusted. This
corresponds to what the OpenSolaris dad(7D) driver does except that
the latter only tweaks sectors and effectively limits the mediasize
to 128GB so the cylinders and heads fields won't ever overflow. Not
limiting the mediasize is a compromise between allowing to use Sun
disk label as far as possible and being able to use the entire disk
with another disk label.
This allows to use the full capacity of large IDE disks if they were
not labeled under (Open)Solaris (in both ways of the meaning).

MFC after:	2 weeks

sys/conf/files.sparc64

@@ -88,6 +88,7 @@ sparc64/pci/psycho.c		optional	pci
 sparc64/sbus/dma_sbus.c		optional	sbus
 sparc64/sbus/sbus.c		optional	sbus
 sparc64/sbus/lsi64854.c		optional	sbus
+sparc64/sparc64/ata_machdep.c	optional	atadisk
 sparc64/sparc64/autoconf.c	standard
 sparc64/sparc64/bus_machdep.c	standard
 sparc64/sparc64/cache.c		standard

sys/sparc64/include/md_var.h

@@ -60,4 +60,17 @@ cpu_block_zero_t spitfire_block_zero;
 extern	cpu_block_copy_t *cpu_block_copy;
 extern	cpu_block_zero_t *cpu_block_zero;
 
+/*
+ * Given that the Sun disk label only uses 16-bit fields for cylinders,
+ * heads and sectors we might need to adjust the geometry of large IDE
+ * disks.
+ * We have to have a knowledge that a device_t is a struct device * here
+ * to avoid including too many things from this file.
+ */
+struct disk;
+struct device;
+void sparc64_ad_firmware_geom_adjust(struct device *dev, struct disk *disk);
+#define	ad_firmware_geom_adjust(dev, dsk)				\
+	sparc64_ad_firmware_geom_adjust(dev, dsk)
+
 #endif /* !_MACHINE_MD_VAR_H_ */

sys/sparc64/sparc64/ata_machdep.c

@@ -0,0 +1,52 @@
+/*-
+ * Copyright (c) 2008 Marius Strobl <marius@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <geom/geom_disk.h>
+#include <machine/md_var.h>
+
+void
+sparc64_ad_firmware_geom_adjust(device_t dev, struct disk *disk)
+{
+
+	/*
+	 * The Sun disk label only uses 16-bit fields for cylinders,
+	 * heads and sectors so the geometry of large IDE disks has
+	 * to be adjusted.  If the disk is > 32GB at 16 heads and 63
+	 * sectors, the sectors have to be adjusted to 255.  If the
+	 * the disk is even > 128GB, additionally adjust the heads
+	 * to 255.
+	 * XXX the OpenSolaris dad(7D) driver limits the mediasize
+	 * to 128GB.
+	 */
+	if (disk->d_mediasize > (off_t)65535 * 16 * 63 * disk->d_sectorsize)
+		disk->d_fwsectors = 255;
+	if (disk->d_mediasize > (off_t)65535 * 16 * 255 * disk->d_sectorsize)
+		disk->d_fwheads = 255;
+}