1*47672Scael.\" Copyright (c) 1990, 1991 Regents of the University of California. 2*47672Scael.\" All rights reserved. 344666Sbostic.\" 4*47672Scael.\" %sccs.include.redist.man% 544666Sbostic.\" 6*47672Scael.\" @(#)mem.4 5.2 (Berkeley) 03/27/91 7*47672Scael.\" 8*47672Scael.Dd 9*47672Scael.Dt MEM 4 hp300 10*47672Scael.Os 11*47672Scael.Sh NAME 12*47672Scael.Nm mem , 13*47672Scael.Nm kmem 14*47672Scael.Nd main memory 15*47672Scael.Sh DESCRIPTION 1644666SbosticThe file 17*47672Scael.Nm /dev/mem 18*47672Scaelis an interface to the physical memory of the 19*47672Scaelcomputer. 20*47672ScaelByte offsets in this file are interpreted as physical memory addresses. 21*47672ScaelReading and writing this file is equivalent to reading and writing 22*47672Scaelmemory itself. 23*47672ScaelAn error will be returned if an attempt is made to reference 24*47672Scaelan offset outside of 25*47672Scael.Nm /dev/mem . 26*47672Scael.Pp 27*47672ScaelKernel virtual memory is accessed via the file 28*47672Scael.Nm /dev/kmem 29*47672Scaelin the same manner as 30*47672Scael.Nm /dev/mem . 31*47672ScaelOnly kernel virtual addresses that are currently mapped to memory are allowed. 32*47672Scael.Sh HP300 33*47672ScaelOn the 34*47672Scael.Tn HP300 , 35*47672Scaelthe last byte of physical memory is always 36*47672Scael.Li 0xFFFFFFFF . 37*47672ScaelTherefore, on an 38*47672Scael.Tn HP300 39*47672Scaelwith 40*47672Scael8Mb of memory, physical memory would start 41*47672Scaelat 42*47672Scael.Li 0xFF800000 . 43*47672ScaelOn the 44*47672Scael.Tn HP300 , 45*47672Scaelkernel virtual memory runs from 46*47672Scael.Li 0 47*47672Scaelto about 48*47672Scael.Li 0x2400000 . 49*47672Scael.Sh FILES 50*47672Scael.Bl -tag -width /dev/kmem -compact 51*47672Scael.It Pa /dev/mem 52*47672Scael.It Pa /dev/kmem 53*47672Scael.El 54*47672Scael.Sh HISTORY 55*47672ScaelThe files 56*47672Scael.Nm mem 57*47672Scaeland 58*47672Scael.Nm kmem 59*47672Scaelappeared in 60*47672Scael.At v6 . 61