ia64/linux-2.6.18-xen.hg

annotate Documentation/hw_random.txt @ 524:7f8b544237bf

netfront: Allow netfront in domain 0.

This is useful if your physical network device is in a utility domain.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Apr 15 15:18:58 2008 +0100 (2008-04-15)
parents 831230e53067
children
rev   line source
ian@0 1 Hardware driver for Intel/AMD/VIA Random Number Generators (RNG)
ian@0 2 Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
ian@0 3 Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
ian@0 4
ian@0 5 Introduction:
ian@0 6
ian@0 7 The hw_random device driver is software that makes use of a
ian@0 8 special hardware feature on your CPU or motherboard,
ian@0 9 a Random Number Generator (RNG).
ian@0 10
ian@0 11 In order to make effective use of this device driver, you
ian@0 12 should download the support software as well. Download the
ian@0 13 latest version of the "rng-tools" package from the
ian@0 14 hw_random driver's official Web site:
ian@0 15
ian@0 16 http://sourceforge.net/projects/gkernel/
ian@0 17
ian@0 18 About the Intel RNG hardware, from the firmware hub datasheet:
ian@0 19
ian@0 20 The Firmware Hub integrates a Random Number Generator (RNG)
ian@0 21 using thermal noise generated from inherently random quantum
ian@0 22 mechanical properties of silicon. When not generating new random
ian@0 23 bits the RNG circuitry will enter a low power state. Intel will
ian@0 24 provide a binary software driver to give third party software
ian@0 25 access to our RNG for use as a security feature. At this time,
ian@0 26 the RNG is only to be used with a system in an OS-present state.
ian@0 27
ian@0 28 Theory of operation:
ian@0 29
ian@0 30 Character driver. Using the standard open()
ian@0 31 and read() system calls, you can read random data from
ian@0 32 the hardware RNG device. This data is NOT CHECKED by any
ian@0 33 fitness tests, and could potentially be bogus (if the
ian@0 34 hardware is faulty or has been tampered with). Data is only
ian@0 35 output if the hardware "has-data" flag is set, but nevertheless
ian@0 36 a security-conscious person would run fitness tests on the
ian@0 37 data before assuming it is truly random.
ian@0 38
ian@0 39 /dev/hwrandom is char device major 10, minor 183.
ian@0 40
ian@0 41 Driver notes:
ian@0 42
ian@0 43 * FIXME: support poll(2)
ian@0 44
ian@0 45 NOTE: request_mem_region was removed, for two reasons:
ian@0 46 1) Only one RNG is supported by this driver, 2) The location
ian@0 47 used by the RNG is a fixed location in MMIO-addressable memory,
ian@0 48 3) users with properly working BIOS e820 handling will always
ian@0 49 have the region in which the RNG is located reserved, so
ian@0 50 request_mem_region calls always fail for proper setups.
ian@0 51 However, for people who use mem=XX, BIOS e820 information is
ian@0 52 -not- in /proc/iomem, and request_mem_region(RNG_ADDR) can
ian@0 53 succeed.
ian@0 54
ian@0 55 Driver details:
ian@0 56
ian@0 57 Based on:
ian@0 58 Intel 82802AB/82802AC Firmware Hub (FWH) Datasheet
ian@0 59 May 1999 Order Number: 290658-002 R
ian@0 60
ian@0 61 Intel 82802 Firmware Hub: Random Number Generator
ian@0 62 Programmer's Reference Manual
ian@0 63 December 1999 Order Number: 298029-001 R
ian@0 64
ian@0 65 Intel 82802 Firmware HUB Random Number Generator Driver
ian@0 66 Copyright (c) 2000 Matt Sottek <msottek@quiknet.com>
ian@0 67
ian@0 68 Special thanks to Matt Sottek. I did the "guts", he
ian@0 69 did the "brains" and all the testing.