Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/Documentation/hw_random.txt
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Tag kernel26-2.6.12-alx-r9
1 | Hardware driver for Intel/AMD/VIA Random Number Generators (RNG) |
2 | Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com> |
3 | Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> |
4 | |
5 | Introduction: |
6 | |
7 | The hw_random device driver is software that makes use of a |
8 | special hardware feature on your CPU or motherboard, |
9 | a Random Number Generator (RNG). |
10 | |
11 | In order to make effective use of this device driver, you |
12 | should download the support software as well. Download the |
13 | latest version of the "rng-tools" package from the |
14 | hw_random driver's official Web site: |
15 | |
16 | http://sourceforge.net/projects/gkernel/ |
17 | |
18 | About the Intel RNG hardware, from the firmware hub datasheet: |
19 | |
20 | The Firmware Hub integrates a Random Number Generator (RNG) |
21 | using thermal noise generated from inherently random quantum |
22 | mechanical properties of silicon. When not generating new random |
23 | bits the RNG circuitry will enter a low power state. Intel will |
24 | provide a binary software driver to give third party software |
25 | access to our RNG for use as a security feature. At this time, |
26 | the RNG is only to be used with a system in an OS-present state. |
27 | |
28 | Theory of operation: |
29 | |
30 | Character driver. Using the standard open() |
31 | and read() system calls, you can read random data from |
32 | the hardware RNG device. This data is NOT CHECKED by any |
33 | fitness tests, and could potentially be bogus (if the |
34 | hardware is faulty or has been tampered with). Data is only |
35 | output if the hardware "has-data" flag is set, but nevertheless |
36 | a security-conscious person would run fitness tests on the |
37 | data before assuming it is truly random. |
38 | |
39 | /dev/hwrandom is char device major 10, minor 183. |
40 | |
41 | Driver notes: |
42 | |
43 | * FIXME: support poll(2) |
44 | |
45 | NOTE: request_mem_region was removed, for two reasons: |
46 | 1) Only one RNG is supported by this driver, 2) The location |
47 | used by the RNG is a fixed location in MMIO-addressable memory, |
48 | 3) users with properly working BIOS e820 handling will always |
49 | have the region in which the RNG is located reserved, so |
50 | request_mem_region calls always fail for proper setups. |
51 | However, for people who use mem=XX, BIOS e820 information is |
52 | -not- in /proc/iomem, and request_mem_region(RNG_ADDR) can |
53 | succeed. |
54 | |
55 | Driver details: |
56 | |
57 | Based on: |
58 | Intel 82802AB/82802AC Firmware Hub (FWH) Datasheet |
59 | May 1999 Order Number: 290658-002 R |
60 | |
61 | Intel 82802 Firmware Hub: Random Number Generator |
62 | Programmer's Reference Manual |
63 | December 1999 Order Number: 298029-001 R |
64 | |
65 | Intel 82802 Firmware HUB Random Number Generator Driver |
66 | Copyright (c) 2000 Matt Sottek <msottek@quiknet.com> |
67 | |
68 | Special thanks to Matt Sottek. I did the "guts", he |
69 | did the "brains" and all the testing. |