| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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. |