[src/trunk]: src/sys/arch/sparc64/dev Comment describing the IOMMU DVMA addre...

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

details:   https://anonhg.NetBSD.org/src/rev/2398d4e6762f
branches:  trunk
changeset: 487789:2398d4e6762f
user:      eeh <eeh%NetBSD.org@localhost>
date:      Mon Jun 12 23:19:05 2000 +0000

description:
Comment describing the IOMMU DVMA address space layout.

diffstat:

 sys/arch/sparc64/dev/iommureg.h |  25 ++++++++++++++++++++++++-
 1 files changed, 24 insertions(+), 1 deletions(-)

diffs (39 lines):

diff -r d081bbfc8605 -r 2398d4e6762f sys/arch/sparc64/dev/iommureg.h
--- a/sys/arch/sparc64/dev/iommureg.h   Mon Jun 12 23:06:59 2000 +0000
+++ b/sys/arch/sparc64/dev/iommureg.h   Mon Jun 12 23:19:05 2000 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: iommureg.h,v 1.4 2000/06/08 15:23:44 eeh Exp $ */
+/*     $NetBSD: iommureg.h,v 1.5 2000/06/12 23:19:05 eeh Exp $ */
 
 /*
  * Copyright (c) 1992, 1993
@@ -97,6 +97,29 @@
 #define IOTTE_C                0x0000000000000010LL    /* Accesses to cacheable space */
 #define IOTTE_W                0x0000000000000002LL    /* Writeable */
 
+/*
+ * On sun4u each bus controller has a separate IOMMU.  The IOMMU has 
+ * a TSB which must be page aligned and physically contiguous.  Mappings
+ * can be of 8K IOMMU pages or 64K IOMMU pages.  We use 8K for compatibility
+ * with the CPU's MMU.
+ *
+ * IOMMU TSBs using 8K pages can map the following size segments:
+ *
+ *     VA size         VA base         TSB size        tsbsize
+ *     --------        --------        ---------       -------
+ *     8MB             ff800000        8K              0
+ *     16MB            ff000000        16K             1
+ *     32MB            fe000000        32K             2
+ *     64MB            fc000000        64K             3
+ *     128MB           f8000000        128K            4
+ *     256MB           f0000000        256K            5
+ *     512MB           e0000000        512K            6
+ *     1GB             c0000000        1MB             7
+ *
+ * The UltraSPARC IIi IOMMU only seems to support 1GB VA size.
+ */
+
+
 #define IOTSB_VEND     (0xffffffffffffffffLL<<PGSHIFT)
 #define IOTSB_VSTART(sz)       (u_int)(IOTSB_VEND << ((sz)+10))