Module Name: src
Committed By: riastradh
Date: Tue Jun 4 21:43:13 UTC 2024
Modified Files:
src/share/man/man9: bus_dma.9
Log Message:
bus_dma(9): Document BUS_DMA_PREFETCHABLE.
Like BUS_DMA_NOCACHE. Doesn't absolve you of the need for
bus_dmamap_sync, but if you later pass the vaddr to bus_dmamap_load,
the DMA map might notice the mapping is write-combining and use this
to make bus_dmamap_sync cheaper.
PR kern/58309
To generate a diff of this commit:
cvs rdiff -u -r1.68 -r1.69 src/share/man/man9/bus_dma.9
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man9/bus_dma.9
diff -u src/share/man/man9/bus_dma.9:1.68 src/share/man/man9/bus_dma.9:1.69
--- src/share/man/man9/bus_dma.9:1.68 Sat Feb 17 08:27:46 2024
+++ src/share/man/man9/bus_dma.9 Tue Jun 4 21:43:13 2024
@@ -1,4 +1,4 @@
-.\" $NetBSD: bus_dma.9,v 1.68 2024/02/17 08:27:46 skrll Exp $
+.\" $NetBSD: bus_dma.9,v 1.69 2024/06/04 21:43:13 riastradh Exp $
.\"
.\" Copyright (c) 1996, 1997, 1998, 2001, 2005, 2006 The NetBSD Foundation, Inc.
.\" All rights reserved.
@@ -717,9 +717,20 @@ function.
This flag is a
.Em hint
to machine-dependent code.
-If possible, map the uncached memory.
+If possible, map the memory uncached.
This flag may be useful in the case that the memory cache causes unexpected
behavior of the device.
+.Pp
+Exclusive with
+.Dv BUS_DMA_PREFETCHABLE .
+.It Dv BUS_DMA_PREFETCHABLE
+This flag is a
+.Em hint
+to machine-dependent code.
+If possible, map the memory prefetchable/write-combining.
+.Pp
+Exclusive with
+.Dv BUS_DMA_NOCACHE .
.El
.El
.Pp
