PHYS(2)             UNIX Programmer's 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 _s_e_g_r_e_g specifies a process virtual (data-space)
     address range of 8K bytes starting at virtual address
     _s_e_g_r_e_gx8K bytes.  This address range is mapped into physical
     address _p_h_y_s_a_d_d_rx64 bytes.  Only the first _s_i_z_ex64 bytes of
     this mapping is addressable.  If _s_i_z_e 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]	    _S_e_g_r_e_g is less than 0 or greater than 7.

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

SEE ALSO
     PDP-11 segmentation hardware

BUGS
     On systems with ENABLE/34(tm) memory mapping boards, _p_h_y_s
     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.

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










Printed 11/26/99	January 22, 1987			1