2 .\" Copyright (c) 2002-2015 Mark R V Murray
3 .\" All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
8 .\" 1. Redistributions of source code must retain the above copyright
9 .\" notice, this list of conditions and the following disclaimer.
10 .\" 2. Redistributions in binary form must reproduce the above copyright
11 .\" notice, this list of conditions and the following disclaimer in the
12 .\" documentation and/or other materials provided with the distribution.
14 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
19 .\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20 .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
21 .\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
22 .\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 .Nd gather entropy from the kernel for the entropy device
38 .Fo random_harvest_direct
41 .Fa "enum esource source"
44 .Fo random_harvest_fast
47 .Fa "enum esource source"
50 .Fo random_harvest_queue
53 .Fa "enum esource source"
58 functions are used by device drivers
59 and other kernel processes to pass data
60 that is considered (at least partially) stochastic
61 to the entropy device.
63 The caller should pass
64 a pointer pointing to the
70 contains the number of bytes pointed to.
74 the values enumerated in
75 .Pa sys/dev/random.h .
76 and is used to indicate the source of the entropy.
79 .Fo random_harvest_direct
83 before any multitasking
87 .Fn random_harvest_fast
95 Some entropy is sacrificed,
96 but the high rate of supply
97 will compensate for this.
100 .Fn random_harvest_queue
102 for general harvesting
104 choice for most entropy sources
108 Interrupt harvesting has been
110 for the kernel programmer.
111 If a device driver registers an interrupt handler
115 .Xr bus_setup_intr 9 ,
116 then it is only necessary to
121 argument to have that interrupt source
122 be used for entropy harvesting.
123 This should be done wherever practicable.
131 entropy device and supporting documentation was written by
132 .An Mark R V Murray .