1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)mem.4 8.1 (Berkeley) 06/05/93 7.\" 8.Dd 9.Dt MEM 4 hp300 10.Os 11.Sh NAME 12.Nm mem , 13.Nm kmem 14.Nd main memory 15.Sh DESCRIPTION 16The file 17.Nm /dev/mem 18is an interface to the physical memory of the 19computer. 20Byte offsets in this file are interpreted as physical memory addresses. 21Reading and writing this file is equivalent to reading and writing 22memory itself. 23An error will be returned if an attempt is made to reference 24an offset outside of 25.Nm /dev/mem . 26.Pp 27Kernel virtual memory is accessed via the file 28.Nm /dev/kmem 29in the same manner as 30.Nm /dev/mem . 31Only kernel virtual addresses that are currently mapped to memory are allowed. 32.Sh HP300 33On the 34.Tn HP300 , 35the last byte of physical memory is always 36.Li 0xFFFFFFFF . 37Therefore, on an 38.Tn HP300 39with 408Mb of memory, physical memory would start 41at 42.Li 0xFF800000 . 43On the 44.Tn HP300 , 45kernel virtual memory runs from 46.Li 0 47to about 48.Li 0x2400000 . 49.Sh FILES 50.Bl -tag -width /dev/kmem -compact 51.It Pa /dev/mem 52.It Pa /dev/kmem 53.El 54.Sh HISTORY 55The files 56.Nm mem 57and 58.Nm kmem 59appeared in 60.At v6 . 61