projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
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. |