MEM(4) (HP700)

MEM(4) | Kernel Interfaces Manual (HP700) | MEM(4)

# NAME

mem, kmem — memory files and memory controller

# SYNOPSIS

mem* at mainbus0

# 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 hp700, the physical memory range is always contiguous and starts at address 0; kernel virtual memory begins at address 0 as well.

The writeability of the /dev/mem and /dev/kmem special files are controlled by the system securelevel in addition to the filesystem permissions.

# FILES

/dev/mem
/dev/kmem

# HISTORY

The mem driver originates from OpenBSD. It was ported to NetBSD 1.6 by Matthew Fredette.

# BUGS

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

March 16, 2004 | NetBSD 5.99