bsd man page for phys

PHYS(2) 							System Calls Manual							   PHYS(2)

NAME
       phys - allow a process to access physical addresses (2BSD)

SYNOPSIS
       phys(segreg, size, physaddr)
       unsigned int segreg, size, physaddr;

DESCRIPTION
       The  argument  segreg specifies a process virtual (data-space) address range of 8K bytes starting at virtual address segregx8K bytes.  This
       address range is mapped into physical address physaddrx64 bytes.  Only the first sizex64 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(7, 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.

ERRORS
       [EPERM]	      The process's effective user ID is not the super-user.

       [EINVAL]       Segreg is less than 0 or greater than 7.

       [EINVAL]       Size is less than 0 or greater than 128.

SEE ALSO
       PDP-11 segmentation hardware

BUGS
       On systems with ENABLE/34(tm) memory mapping boards, phys cannot be used to map in the I/O page.

       This system call is very dangerous.  It is not considered a permanent part of the system.

       Phys is unique to the PDP-11 and 2BSD; its use is discouraged.

3rd Berkeley Distribution					 January 22, 1987							   PHYS(2)