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 segreg×8K bytes. This address range is mapped into physical address physaddr×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(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.