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segment(3): document fixed segment creation

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cinap_lenrek 2015-04-12 16:38:39 +02:00
parent d9880518f0
commit 98a7eae9c0
1 changed files with 10 additions and 2 deletions
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12
sys/man/3/segment
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@ -56,7 +56,7 @@ retrieves and sets the segment's properties.
There is only one control message, which sets the segment's There is only one control message, which sets the segment's
virtual address and length in bytes: virtual address and length in bytes:
.EX .EX
va \fIaddress length\fP va \fIaddress length type\fP
.EE .EE
.I Address .I Address
is automatically rounded down to a page boundary and is automatically rounded down to a page boundary and
@ -64,6 +64,12 @@ is automatically rounded down to a page boundary and
is rounded up to end the segment at a page boundary. is rounded up to end the segment at a page boundary.
The segment will reside at the same virtual address in The segment will reside at the same virtual address in
all processes sharing it. 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 When the segment
is attached using is attached using
.IR segattach, .IR segattach,
@ -75,7 +81,9 @@ Once the address and length are set, they cannot be reset.
.PP .PP
Reading the control file Reading the control file
returns a message of the same format with the segment's actual 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 .PP
Opening Opening
.B data .B data