xref: /csrg-svn/share/man/man4/man4.vax/mem.4 (revision 47674) 
1*47674Scael.\" Copyright (c) 1980, 1991 Regents of the University of California.
2*47674Scael.\" All rights reserved.
320677Smckusick.\"
4*47674Scael.\" %sccs.include.redist.man%
520677Smckusick.\"
6*47674Scael.\"     @(#)mem.4	6.3 (Berkeley) 03/27/91
7*47674Scael.\"
8*47674Scael.Dd
9*47674Scael.Dt MEM 4 vax
10*47674Scael.Os BSD 4
11*47674Scael.Sh NAME
12*47674Scael.Nm mem ,
13*47674Scael.Nm kmem ,
14*47674Scael.Nm kUmem
15*47674Scael.Nd memory files
16*47674Scael.Sh DESCRIPTION
17*47674ScaelThe special file
18*47674Scael.Nm /dev/mem
19*47674Scaelis an interface to the physical memory of the computer.
20*47674ScaelByte offsets in this file are interpreted as physical memory addresses.
21*47674ScaelReading and writing this file is equivalent to reading and writing
22*47674Scaelmemory itself.
23*47674ScaelOnly offsets within the bounds of
24*47674Scael.Nm /dev/mem
25*47674Scaelare allowed.
26*47674Scael.Pp
27*47674ScaelKernel virtual memory is accessed through the interface
28*47674Scael.Nm /dev/kmem
29*47674Scaelin the same manner as
30*47674Scael.Nm /dev/mem .
31*47674ScaelOnly kernel virtual addresses that are currently mapped to memory are allowed.
32*47674Scael.Pp
3320677SmckusickThe file
34*47674Scael.Nm /dev/kUmem
3528257Skarelsalso refers to kernel virtual memory,
36*47674Scaelbut may be used to access areas mapped to
37*47674Scael.Tn UNIBUS
38*47674Scaeladdress space
39*47674Scaeland other
40*47674Scael.Tn I/O
41*47674Scaelareas.
4228257SkarelsIt forces all accesses to use word (short integer) accesses.
43*47674Scael.Pp
44*47674ScaelOn the
45*47674Scael.Tn VAX
46*47674Scael11/780,
47*47674Scaelthe
48*47674Scael.Tn I/O
49*47674Scaelspace base address is
50*47674Scael20000000(16);
51*47674Scaelon an 11/750
52*47674Scaelthe
53*47674Scael.Tn I/O space addresses are of the form fxxxxx(16).
54*47674ScaelOn all
55*47674Scael.Tn VAX Ns 'en
56*47674Scaelthe
57*47674Scaelper-process data
58*47674Scaelsize
59*47674Scaelfor the current process
60*47674Scaelis
61*47674Scael.Dv UPAGES
62*47674Scaellong and ends at the virtual address 80000000(16).
63*47674Scael.Sh FILES
64*47674Scael.Bl -tag -width Pa -compact
65*47674Scael.It Pa /dev/mem
66*47674Scael.It Pa /dev/kmem
67*47674Scael.It Pa /dev/kUmem
68*47674Scael.El
69*47674Scael.Sh HISTORY
70*47674ScaelThe
71*47674Scael.Nm mem ,
72*47674Scael.Nm kmem
73*47674Scaelfiles appeared in
74*47674Scael.At v6 .
75*47674ScaelThe file
76*47674Scael.Nm kUmem
77*47674Scaelappeared in
78*47674Scael.Bx 3.0 .
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