mem(4) - NetBSD Manual Pages

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MEM(4)               NetBSD/hppa Kernel Interfaces Manual               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 hppa, 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 con- trolled by the system securelevel in addition to the filesystem permis- sions.
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 hppa/cpu(4) device probe. NetBSD 9.99 February 17, 2017 NetBSD 9.99
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