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28 .\" @(#)mem.4 5.3 (Berkeley) 5/2/91
29 .\" $FreeBSD: src/share/man/man4/mem.4,v 1.7.2.5 2002/02/27 03:39:23 dd Exp $
41 is an interface to the physical memory of the computer.
42 Byte offsets in this file are interpreted as physical memory addresses.
43 Reading and writing this file is equivalent to reading and writing
45 Only offsets within the bounds of
49 Kernel virtual memory is accessed through the interface
53 Only kernel virtual addresses that are currently mapped to memory are allowed.
59 memory space begins at physical address 0x000a0000
60 and runs to 0x00100000.
64 for the current process
67 long, and ends at virtual
70 Several architectures allow attributes to be associated with ranges of physical
72 These attributes can be manipulated via
76 Declarations and data types are to be found in
79 The specific attributes, and number of programmable ranges may vary between
81 The full set of supported attributes is:
82 .Bl -tag -width indent
83 .It Dv MDF_UNCACHEABLE
84 The region is not cached.
85 .It Dv MDF_WRITECOMBINE
86 Writes to the region may be combined or performed out of order.
87 .It Dv MDF_WRITETHROUGH
88 Writes to the region are committed synchronously.
90 Writes to the region are committed asynchronously.
91 .It Dv MDF_WRITEPROTECT
92 The region cannot be written to.
95 Memory ranges are described by
96 .Vt struct mem_range_desc :
97 .Bd -literal -offset indent
98 u_int64_t mr_base; /\(** physical base address \(**/
99 u_int64_t mr_len; /\(** physical length of region \(**/
100 int mr_flags; /\(** attributes of region \(**/
104 In addition to the region attributes listed above, the following flags
105 may also be set in the
108 .Bl -tag -width indent
110 The region's base address cannot be changed.
112 The region's length cannot be changed.
114 The region is believed to have been established by the system firmware.
116 The region is currently active.
118 We believe the region to be invalid or otherwise erroneous.
120 The region cannot be disabled.
122 The region is currently owned by another process and may not be
126 Operations are performed using
127 .Fa struct mem_range_op :
128 .Bd -literal -offset indent
129 struct mem_range_desc *mo_desc;
135 ioctl is used to retrieve current memory range attributes.
138 is set to 0, it will be updated with the total number of memory range
140 If greater than 0, the array at
142 will be filled with a corresponding number of descriptor structures,
143 or the maximum, whichever is less.
147 ioctl is used to add, alter and remove memory range attributes. A range
150 flag may not be removed; a range with the
152 flag may not be removed or updated.
156 .Dv MEMRANGE_SET_UPDATE
157 to update an existing or establish a new range, or to
158 .Dv MEMRANGE_SET_REMOVE
161 .Bl -tag -width /dev/kmem -compact
168 Memory range operations are not supported on this architecture.
170 No memory range descriptors are available (eg. firmware has not enabled
173 The memory range supplied as an argument is invalid or overlaps another
174 range in a fashion not supported by this architecture.
176 An attempt to remove or update a range failed because the range is busy.
178 An attempt to create a new range failed due to a shortage of hardware
179 resources (eg. descriptor slots).
181 An attempt to remove a range failed because no range matches the descriptor
182 base/length supplied.
184 An attempt to remove a range failed because the range is permanently
196 The ioctl interface for memory range attributes was added in
199 Busy range attributes are not yet managed correctly.