1.\" Copyright (c) 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)mem.4 5.3 (Berkeley) 5/2/91 33.\" $FreeBSD: src/share/man/man4/mem.4,v 1.7.2.5 2002/02/27 03:39:23 dd Exp $ 34.\" $DragonFly: src/share/man/man4/mem.4,v 1.8 2007/05/17 08:19:01 swildner Exp $ 35.\" 36.Dd May 2, 1991 37.Dt MEM 4 38.Os 39.Sh NAME 40.Nm mem , 41.Nm kmem 42.Nd memory files 43.Sh DESCRIPTION 44The special file 45.Pa /dev/mem 46is an interface to the physical memory of the computer. 47Byte offsets in this file are interpreted as physical memory addresses. 48Reading and writing this file is equivalent to reading and writing 49memory itself. 50Only offsets within the bounds of 51.Pa /dev/mem 52are allowed. 53.Pp 54Kernel virtual memory is accessed through the interface 55.Pa /dev/kmem 56in the same manner as 57.Pa /dev/mem . 58Only kernel virtual addresses that are currently mapped to memory are allowed. 59.Pp 60On 61.Tn ISA 62the 63.Tn I/O 64memory space begins at physical address 0x000a0000 65and runs to 0x00100000. 66The 67per-process data 68size 69for the current process 70is 71.Dv UPAGES 72long, and ends at virtual 73address 0xf0000000. 74.Sh IOCTL INTERFACE 75Several architectures allow attributes to be associated with ranges of physical 76memory. 77These attributes can be manipulated via 78.Fn ioctl 79calls performed on 80.Pa /dev/mem . 81Declarations and data types are to be found in 82.In sys/memrange.h . 83.Pp 84The specific attributes, and number of programmable ranges may vary between 85architectures. 86The full set of supported attributes is: 87.Bl -tag -width indent 88.It Dv MDF_UNCACHEABLE 89The region is not cached. 90.It Dv MDF_WRITECOMBINE 91Writes to the region may be combined or performed out of order. 92.It Dv MDF_WRITETHROUGH 93Writes to the region are committed synchronously. 94.It Dv MDF_WRITEBACK 95Writes to the region are committed asynchronously. 96.It Dv MDF_WRITEPROTECT 97The region cannot be written to. 98.El 99.Pp 100Memory ranges are described by 101.Vt struct mem_range_desc : 102.Bd -literal -offset indent 103u_int64_t mr_base; /\(** physical base address \(**/ 104u_int64_t mr_len; /\(** physical length of region \(**/ 105int mr_flags; /\(** attributes of region \(**/ 106char mr_owner[8]; 107.Ed 108.Pp 109In addition to the region attributes listed above, the following flags 110may also be set in the 111.Fa mr_flags 112field: 113.Bl -tag -width indent 114.It Dv MDF_FIXBASE 115The region's base address cannot be changed. 116.It Dv MDF_FIXLEN 117The region's length cannot be changed. 118.It Dv MDF_FIRMWARE 119The region is believed to have been established by the system firmware. 120.It Dv MDF_ACTIVE 121The region is currently active. 122.It Dv MDF_BOGUS 123We believe the region to be invalid or otherwise erroneous. 124.It Dv MDF_FIXACTIVE 125The region cannot be disabled. 126.It Dv MDF_BUSY 127The region is currently owned by another process and may not be 128altered. 129.El 130.Pp 131Operations are performed using 132.Fa struct mem_range_op : 133.Bd -literal -offset indent 134struct mem_range_desc *mo_desc; 135int mo_arg[2]; 136.Ed 137.Pp 138The 139.Dv MEMRANGE_GET 140ioctl is used to retrieve current memory range attributes. 141If 142.Va mo_arg[0] 143is set to 0, it will be updated with the total number of memory range 144descriptors. 145If greater than 0, the array at 146.Va mo_desc 147will be filled with a corresponding number of descriptor structures, 148or the maximum, whichever is less. 149.Pp 150The 151.Dv MEMRANGE_SET 152ioctl is used to add, alter and remove memory range attributes. A range 153with the 154.Dv MDF_FIXACTIVE 155flag may not be removed; a range with the 156.Dv MDF_BUSY 157flag may not be removed or updated. 158.Pp 159.Va mo_arg[0] 160should be set to 161.Dv MEMRANGE_SET_UPDATE 162to update an existing or establish a new range, or to 163.Dv MEMRANGE_SET_REMOVE 164to remove a range. 165.Sh RETURN VALUES 166.Bl -tag -width Er 167.It Bq Er EOPNOTSUPP 168Memory range operations are not supported on this architecture. 169.It Bq Er ENXIO 170No memory range descriptors are available (eg. firmware has not enabled 171any). 172.It Bq Er EINVAL 173The memory range supplied as an argument is invalid or overlaps another 174range in a fashion not supported by this architecture. 175.It Bq Er EBUSY 176An attempt to remove or update a range failed because the range is busy. 177.It Bq Er ENOSPC 178An attempt to create a new range failed due to a shortage of hardware 179resources (eg. descriptor slots). 180.It Bq Er ENOENT 181An attempt to remove a range failed because no range matches the descriptor 182base/length supplied. 183.It Bq Er EPERM 184An attempt to remove a range failed because the range is permanently 185enabled. 186.El 187.Sh FILES 188.Bl -tag -width /dev/kmem -compact 189.It Pa /dev/mem 190.It Pa /dev/kmem 191.El 192.Sh SEE ALSO 193.Xr memcontrol 8 194.Sh HISTORY 195The 196.Nm mem 197and 198.Nm kmem 199files appeared in 200.At v6 . 201The ioctl interface for memory range attributes was added in 202.Fx 3.2 . 203.Sh BUGS 204Busy range attributes are not yet managed correctly. 205