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diff --git a/share/man/man4/mem.4 b/share/man/man4/mem.4 new file mode 100644 index 000000000000..5dd2cb98f1ec --- /dev/null +++ b/share/man/man4/mem.4 @@ -0,0 +1,211 @@ +.\" Copyright (c) 1991 The Regents of the University of California. +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)mem.4 5.3 (Berkeley) 5/2/91 +.\" $FreeBSD$ +.\" +.Dd October 3, 2004 +.Dt MEM 4 +.Os +.Sh NAME +.Nm mem , +.Nm kmem +.Nd memory files +.Sh SYNOPSIS +.Cd "device mem" +.Sh DESCRIPTION +The special file +.Pa /dev/mem +is an interface to the physical memory of the computer. +Byte offsets in this file are interpreted as physical memory addresses. +Reading and writing this file is equivalent to reading and writing +memory itself. +Only offsets within the bounds of +.Pa /dev/mem +are allowed. +.Pp +Kernel virtual memory is accessed through the interface +.Pa /dev/kmem +in the same manner as +.Pa /dev/mem . +Only kernel virtual addresses that are currently mapped to memory are allowed. +.Pp +On +.Tn ISA +the +.Tn I/O +memory space begins at physical address 0x000a0000 +and runs to 0x00100000. +The +per-process data +size +for the current process +is +.Dv UPAGES +long, and ends at virtual +address 0xf0000000. +.Sh IOCTL INTERFACE +Several architectures allow attributes to be associated with ranges of physical +memory. +These attributes can be manipulated via +.Fn ioctl +calls performed on +.Pa /dev/mem . +Declarations and data types are to be found in +.In sys/memrange.h . +.Pp +The specific attributes, and number of programmable ranges may vary between +architectures. +The full set of supported attributes is: +.Bl -tag -width indent +.It Dv MDF_UNCACHEABLE +The region is not cached. +.It Dv MDF_WRITECOMBINE +Writes to the region may be combined or performed out of order. +.It Dv MDF_WRITETHROUGH +Writes to the region are committed synchronously. +.It Dv MDF_WRITEBACK +Writes to the region are committed asynchronously. +.It Dv MDF_WRITEPROTECT +The region cannot be written to. +.El +.Pp +Memory ranges are described by +.Vt struct mem_range_desc : +.Bd -literal -offset indent +u_int64_t mr_base; /\(** physical base address \(**/ +u_int64_t mr_len; /\(** physical length of region \(**/ +int mr_flags; /\(** attributes of region \(**/ +char mr_owner[8]; +.Ed +.Pp +In addition to the region attributes listed above, the following flags +may also be set in the +.Fa mr_flags +field: +.Bl -tag -width indent +.It MDF_FIXBASE +The region's base address cannot be changed. +.It MDF_FIXLEN +The region's length cannot be changed. +.It MDF_FIRMWARE +The region is believed to have been established by the system firmware. +.It MDF_ACTIVE +The region is currently active. +.It MDF_BOGUS +We believe the region to be invalid or otherwise erroneous. +.It MDF_FIXACTIVE +The region cannot be disabled. +.It MDF_BUSY +The region is currently owned by another process and may not be +altered. +.El +.Pp +Operations are performed using +.Fa struct mem_range_op : +.Bd -literal -offset indent +struct mem_range_desc *mo_desc; +int mo_arg[2]; +.Ed +.Pp +The +.Dv MEMRANGE_GET +ioctl is used to retrieve current memory range attributes. +If +.Va mo_arg[0] +is set to 0, it will be updated with the total number of memory range +descriptors. +If greater than 0, the array at +.Va mo_desc +will be filled with a corresponding number of descriptor structures, +or the maximum, whichever is less. +.Pp +The +.Dv MEMRANGE_SET +ioctl is used to add, alter and remove memory range attributes. +A range +with the +.Dv MDF_FIXACTIVE +flag may not be removed; a range with the +.Dv MDF_BUSY +flag may not be removed or updated. +.Pp +.Va mo_arg[0] +should be set to +.Dv MEMRANGE_SET_UPDATE +to update an existing or establish a new range, or to +.Dv MEMRANGE_SET_REMOVE +to remove a range. +.Sh RETURN VALUES +.Bl -tag -width Er +.It Bq Er EOPNOTSUPP +Memory range operations are not supported on this architecture. +.It Bq Er ENXIO +No memory range descriptors are available (e.g.\& firmware has not enabled +any). +.It Bq Er EINVAL +The memory range supplied as an argument is invalid or overlaps another +range in a fashion not supported by this architecture. +.It Bq Er EBUSY +An attempt to remove or update a range failed because the range is busy. +.It Bq Er ENOSPC +An attempt to create a new range failed due to a shortage of hardware +resources (e.g.\& descriptor slots). +.It Bq Er ENOENT +An attempt to remove a range failed because no range matches the descriptor +base/length supplied. +.It Bq Er EPERM +An attempt to remove a range failed because the range is permanently +enabled. +.El +.Sh FILES +.Bl -tag -width /dev/kmem -compact +.It Pa /dev/mem +.It Pa /dev/kmem +.El +.Sh SEE ALSO +.Xr kvm 3 , +.Xr memcontrol 8 +.Sh HISTORY +The +.Nm mem +and +.Nm kmem +files appeared in +.At v6 . +The ioctl interface for memory range attributes was added in +.Fx 3.2 . +.Sh BUGS +Busy range attributes are not yet managed correctly. +.Pp +This device is required for all users of +.Xr kvm 3 +to operate. |