1 .\" Copyright (c) 1991 The Regents of the University of California.
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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 $
45 is an interface to the physical memory of the computer.
46 Byte offsets in this file are interpreted as physical memory addresses.
47 Reading and writing this file is equivalent to reading and writing
49 Only offsets within the bounds of
53 Kernel virtual memory is accessed through the interface
57 Only kernel virtual addresses that are currently mapped to memory are allowed.
63 memory space begins at physical address 0x000a0000
64 and runs to 0x00100000.
68 for the current process
71 long, and ends at virtual
74 Several architectures allow attributes to be associated with ranges of physical
75 memory. These attributes can be manipulated via
79 Declarations and data types are to be found in
82 The specific attributes, and number of programmable ranges may vary between
83 architectures. The full set of supported attributes is:
84 .Bl -tag -width indent
86 The region is not cached.
88 Writes to the region may be combined or performed out of order.
90 Writes to the region are committed synchronously.
92 Writes to the region are committed asynchronously.
94 The region cannot be written to.
97 Memory ranges are described by
98 .Fa struct mem_range_desc :
99 .Bd -literal -offset indent
100 u_int64_t mr_base; /\(** physical base address \(**/
101 u_int64_t mr_len; /\(** physical length of region \(**/
102 int mr_flags; /\(** attributes of region \(**/
106 In addition to the region attributes listed above, the following flags
107 may also be set in the
110 .Bl -tag -width indent
112 The region's base address cannot be changed.
114 The region's length cannot be changed.
116 The region is believed to have been established by the system firmare.
118 The region is currently active.
120 We believe the region to be invalid or otherwise erroneous.
122 The region cannot be disabled.
124 The region is currently owned by another process and may not be
128 Operations are performed using
129 .Fa struct mem_range_op :
130 .Bd -literal -offset indent
131 struct mem_range_desc *mo_desc;
137 ioctl is used to retrieve current memory range attributes.
140 is set to 0, it will be updated with the total number of memory range
141 descriptors. If greater than 0, the array at
143 will be filled with a corresponding number of descriptor structures,
144 or the maximum, whichever is less.
148 ioctl is used to add, alter and remove memory range attributes. A range
149 with the MDF_FIXACTIVE flag may not be removed; a range with the MDF_BUSY
150 flag may not be removed or updated.
153 should be set to MEMRANGE_SET_UPDATE to update an existing
154 or establish a new range, or to MEMRANGE_SET_REMOVE to remove a range.
158 Memory range operations are not supported on this architecture.
160 No memory range descriptors are available (eg. firmware has not enabled
163 The memory range supplied as an argument is invalid or overlaps another
164 range in a fashion not supported by this architecture.
166 An attempt to remove or update a range failed because the range is busy.
168 An attempt to create a new range failed due to a shortage of hardware
169 resources (eg. descriptor slots).
171 An attempt to remove a range failed because no range matches the descriptor
172 base/length supplued.
174 An attempt to remove a range failed because the range is permanently
178 Busy range attributes are not yet managed correctly.
180 .Bl -tag -width /dev/kmem -compact
192 The ioctl interface for memory range attributes was added in