ref: 98a7eae9c0cdb31a48c79b34c5f263916a8c1390
parent: d9880518f0d6923561252e290417c0cd2acd26b5
author: cinap_lenrek <[email protected]>
date: Sun Apr 12 12:38:39 EDT 2015
segment(3): document fixed segment creation
--- a/sys/man/3/segment
+++ b/sys/man/3/segment
@@ -56,7 +56,7 @@
There is only one control message, which sets the segment's
virtual address and length in bytes:
.EX
- va \fIaddress length\fP
+ va \fIaddress length type\fP
.EE
.I Address
is automatically rounded down to a page boundary and
@@ -64,6 +64,12 @@
is rounded up to end the segment at a page boundary.
The segment will reside at the same virtual address in
all processes sharing it.
+Optionally,
+.I type
+can be specified as
+.B fixed
+to create a physically continuous segment with a fixed
+physical base address suitable for hardware DMA access.
When the segment
is attached using
.IR segattach,
@@ -75,7 +81,9 @@
.PP
Reading the control file
returns a message of the same format with the segment's actual
-start address and length.
+start address and length. For
+.B fixed
+segments, the type and physical base address are appended.
.PP
Opening
.B data