PHYS
Section: System Calls (2)
Updated: PDP11
Index
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NAME
phys - allow a process to access physical addresses
SYNOPSIS
phys(segreg, size, physadr)
DESCRIPTION
The argument
segreg
specifies a process virtual (data-space) address
range of 8K bytes starting
at virtual address
segreg×8K
bytes.
This address range is mapped into
physical address
physadr×64
bytes.
Only the first
size×64
bytes of this mapping is addressable.
If
size
is zero,
any previous mapping of this
virtual address range is nullified.
For example,
the call
phys(6, 1, 0177775);
will map virtual addresses 0160000-0160077 into
physical addresses 017777500-017777577.
In particular,
virtual address 0160060 is the PDP-11 console
located at physical address 017777560.
This call may only be executed by the super-user.
SEE ALSO
PDP-11 segmentation hardware
DIAGNOSTICS
The function value zero is returned if
the physical mapping is in effect.
The value -1 is returned
if not super-user,
if
segreg
is not in the range 0-7,
if
size
is not in the range 0-127,
or if
the specified
segreg
is already used for other than
a previous call to
phys.
BUGS
This system call is obviously very machine
dependent and very dangerous.
This system call is not considered
a permanent part of the system.
ASSEMBLER
(phys = 52.)
sys phys; segreg; size; physadr
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- SEE ALSO
-
- DIAGNOSTICS
-
- BUGS
-
- ASSEMBLER
-
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