PHYS(2)PHYS(2)NAMEphys - 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 speci‐
fied segreg is already used for other than a previous call to phys.
BUGS
This system call is obviously very machine dependent and very danger‐
ous. This system call is not considered a permanent part of the sys‐
tem.
ASSEMBLER
(phys = 52.)
sys phys; segreg; size; physadr
PDP11 PHYS(2)
