MEM(4)           NetBSD Programmer's Manual (VAX Architecture)          MEM(4)

NNAAMMEE
     mmeemm, kkmmeemm, kkUUmmeemm - memory files

DDEESSCCRRIIPPTTIIOONN
     The special file //ddeevv//mmeemm is an interface to the physical memory of the
     computer.  Byte offsets in this file are interpreted as physical memory
     addresses.  Reading and writing this file is equivalent to reading and
     writing memory itself.  Only offsets within the bounds of //ddeevv//mmeemm are
     allowed.

     Kernel virtual memory is accessed through the interface //ddeevv//kkmmeemm in the
     same manner as //ddeevv//mmeemm. Only kernel virtual addresses that are currently
     mapped to memory are allowed.

     The file //ddeevv//kkUUmmeemm also refers to kernel virtual memory, but may be used
     to access areas mapped to UNIBUS address space and other I/O areas.  It
     forces all accesses to use word (short integer) accesses.

     On the VAX 11/780, the I/O space base address is 20000000(16); on an
     11/750 the I/O space addresses are of the form fxxxxx(16). On all VAX'en
     the per-process data size for the current process is UPAGES long and ends
     at the virtual address 80000000(16).

FFIILLEESS
     /dev/mem
     /dev/kmem
     /dev/kUmem

HHIISSTTOORRYY
     The mmeemm, kkmmeemm files appeared in Version 6 AT&T UNIX.  The file kkUUmmeemm ap-
     peared in 3.0BSD.

4th Berkeley Distribution        June 5, 1993                                1