MEM(4)                OpenBSD Programmer's Manual (HPPA)                MEM(4)

NAME
     mem, kmem - memory files and memory controller

SYNOPSIS
     mem* at mainbus0 flags 0x0000

DESCRIPTION
     The mem driver controls and restricts access to the systems memory by the
     hardware buses and the processor.

     It also provides an interface to userland through the special files
     /dev/mem and /dev/kmem.  Physical memory is accessed through /dev/mem,
     while kernel virtual memory is accessed through /dev/kmem.  Access to
     kernel virtual addresses not currently mapped to memory will fail.  On
     hppa, the physical memory range is always contiguous and starts at ad-
     dress 0; kernel virtual memory begins at address 0 as well.

     The writeability of the /dev/mem and /dev/kmem special files are con-
     trolled by the system securelevel(7), in addition to the filesystem per-
     missions.

FILES
     /dev/mem
     /dev/kmem

SEE ALSO
     securelevel(7)

CAVEATS
     On some systems featuring a ``Viper'' memory controller, OpenBSD may not
     configure bus arbitration correctly, causing the boot process to freeze
     during either mem or cpu(4) device probe.

     In this case, a different initialization strategy can be achieved by set-
     ting flags to 0x0001 (see boot_config(8) for details).

OpenBSD 4.7                      May 31, 2007                                1
