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28 .\" @(#)mem.4 5.3 (Berkeley) 5/2/91
43 is an interface to the physical memory of the computer.
44 Byte offsets in this file are interpreted as physical memory addresses.
45 Reading and writing this file is equivalent to reading and writing
47 Only offsets within the bounds of
51 Kernel virtual memory is accessed through the interface
55 Only kernel virtual addresses that are currently mapped to memory are allowed.
57 On ISA the I/O memory space begins at physical address 0x000a0000
58 and runs to 0x00100000.
62 for the current process
65 long, and ends at virtual
70 ioctl can be used to look up the physical address and NUMA domain of a given
71 virtual address in the calling process' address space.
72 The request is described by
75 uint64_t me_vaddr; /* input */
76 uint64_t me_paddr; /* output */
77 int me_domain; /* output */
78 int me_state; /* output */
82 The ioctl returns an error if the address is not valid.
83 The information returned by
85 may be out of date by the time that the ioctl call returns.
86 Specifically, concurrent system calls, page faults, or system page reclamation
87 activity may have unmapped the virtual page or replaced the backing physical
88 page before the ioctl call returns.
89 Wired pages, e.g., those locked by
91 will not be reclaimed by the system.
95 field provides information about the state of the virtual page:
96 .Bl -tag -width indent
97 .It Dv ME_STATE_INVALID
98 The virtual address is invalid.
100 The virtual address is valid but is not mapped at the time of the ioctl call.
101 .It Dv ME_STATE_MAPPED
102 The virtual address corresponds to a physical page mapping, and the
108 Several architectures allow attributes to be associated with ranges of physical
110 These attributes can be manipulated via
114 Declarations and data types are to be found in
117 The specific attributes, and number of programmable ranges may vary between
119 The full set of supported attributes is:
120 .Bl -tag -width indent
121 .It Dv MDF_UNCACHEABLE
122 The region is not cached.
123 .It Dv MDF_WRITECOMBINE
124 Writes to the region may be combined or performed out of order.
125 .It Dv MDF_WRITETHROUGH
126 Writes to the region are committed synchronously.
128 Writes to the region are committed asynchronously.
129 .It Dv MDF_WRITEPROTECT
130 The region cannot be written to.
133 Memory ranges are described by
135 struct mem_range_desc {
136 uint64_t mr_base; /* physical base address */
137 uint64_t mr_len; /* physical length of region */
138 int mr_flags; /* attributes of region */
143 In addition to the region attributes listed above, the following flags
144 may also be set in the
147 .Bl -tag -width indent
149 The region's base address cannot be changed.
151 The region's length cannot be changed.
153 The region is believed to have been established by the system firmware.
155 The region is currently active.
157 We believe the region to be invalid or otherwise erroneous.
159 The region cannot be disabled.
161 The region is currently owned by another process and may not be
165 Operations are performed using
167 struct mem_range_op {
168 struct mem_range_desc *mo_desc;
175 ioctl is used to retrieve current memory range attributes.
178 is set to 0, it will be updated with the total number of memory range
180 If greater than 0, the array at
182 will be filled with a corresponding number of descriptor structures,
183 or the maximum, whichever is less.
187 ioctl is used to add, alter and remove memory range attributes.
191 flag may not be removed; a range with the
193 flag may not be removed or updated.
197 .Dv MEMRANGE_SET_UPDATE
198 to update an existing or establish a new range, or to
199 .Dv MEMRANGE_SET_REMOVE
205 Memory range operations are not supported on this architecture.
207 No memory range descriptors are available (e.g., firmware has not enabled
210 The memory range supplied as an argument is invalid or overlaps another
211 range in a fashion not supported by this architecture.
213 An attempt to remove or update a range failed because the range is busy.
215 An attempt to create a new range failed due to a shortage of hardware
216 resources (e.g., descriptor slots).
218 An attempt to remove a range failed because no range matches the descriptor
219 base/length supplied.
221 An attempt to remove a range failed because the range is permanently
225 .Bl -tag -width /dev/kmem -compact
239 The ioctl interface for memory range attributes was added in
242 Busy range attributes are not yet managed correctly.
244 This device is required for all users of