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. 

2nd Berkeley Distribution  —  January 22, 1987