[src/trunk]: src/share/man/man4 Explain RBUS_IO_BASE/SIZE.

[gdt <gdt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3e73f5437670
branches:  trunk
changeset: 335250:3e73f5437670
user:      gdt <gdt%NetBSD.org@localhost>
date:      Wed Dec 31 18:14:55 2014 +0000

description:
Explain RBUS_IO_BASE/SIZE.

See also kern/32327.

Adapted from a patch by Bj?rn Johannesson.

diffstat:

 share/man/man4/cardbus.4 |  19 ++++++++++++++-----
 1 files changed, 14 insertions(+), 5 deletions(-)

diffs (44 lines):

diff -r af53ccdfa956 -r 3e73f5437670 share/man/man4/cardbus.4
--- a/share/man/man4/cardbus.4  Wed Dec 31 18:14:14 2014 +0000
+++ b/share/man/man4/cardbus.4  Wed Dec 31 18:14:55 2014 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: cardbus.4,v 1.35 2012/04/25 04:14:03 nakayama Exp $
+.\"    $NetBSD: cardbus.4,v 1.36 2014/12/31 18:14:55 gdt Exp $
 .\"
 .\" Copyright (c) 1999-2006 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,7 +27,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd April 25, 2012
+.Dd December 31, 2014
 .Dt CARDBUS 4
 .Os
 .Sh NAME
@@ -183,9 +183,9 @@
 .Sh BUGS
 .Ss Memory space conflicts
 .Nx
-maps memory on Cardbus and PCMCIA cards in order to access the cards
-(including reading CIS tuples on PCMCIA cards)
-and access the devices using the
+maps memory on Cardbus (and therefore PCMCIA cards behind Cardbus) in
+order to access the cards (including reading CIS tuples on PCMCIA
+cards) and access the devices using the
 .Tn RBUS
 abstraction.
 When the mapping does not work, PCMCIA cards are typically ignored on
@@ -204,3 +204,12 @@
 ARMADA M700:
 .Pp
 .Cd options RBUS_MIN_START="0x20000000"
+.Ss PCMCIA addressing choice
+By default, on i386, the kernel uses RBUS_IO_BASE as 0x4000 and
+RBUS_IO_SIZE as 0x2000.  On some machines, this fails, due to a
+requirement that these addresses fit within 12 bits.  The following
+kernel options have been reported as helpful:
+.Pp
+.Cd options RBUS_IO_BASE="0xa00"
+.Pp
+.Cd options RBUS_IO_SIZE="0x00ff"