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MEM(4) NetBSD/x86 Kernel Interfaces Manual MEM(4)
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mem, kmem -- memory files
The special file /dev/mem 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 /dev/mem are
Kernel virtual memory is accessed through the interface /dev/kmem in the
same manner as /dev/mem. Only kernel virtual addresses that are cur-
rently mapped to memory are allowed.
On ISA the I/O memory space begins at physical address 0x000a0000 and
runs to 0x00100000. The per-process data size for the current process is
UPAGES long, and ends at virtual address 0xfe000000.
The mem, kmem files appeared in Version 6 AT&T UNIX.
NetBSD 9.3 September 23, 2011 NetBSD 9.3