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Diffstat (limited to 'Documentation/hw_random.txt')
| -rw-r--r-- | Documentation/hw_random.txt | 159 |
1 files changed, 87 insertions, 72 deletions
diff --git a/Documentation/hw_random.txt b/Documentation/hw_random.txt index fce1634907d0..121de96e395e 100644 --- a/Documentation/hw_random.txt +++ b/Documentation/hw_random.txt @@ -1,90 +1,105 @@ -Introduction: - - The hw_random framework is software that makes use of a - special hardware feature on your CPU or motherboard, - a Random Number Generator (RNG). The software has two parts: - a core providing the /dev/hwrng character device and its - sysfs support, plus a hardware-specific driver that plugs - into that core. - - To make the most effective use of these mechanisms, you - should download the support software as well. Download the - latest version of the "rng-tools" package from the - hw_random driver's official Web site: - - http://sourceforge.net/projects/gkernel/ - - Those tools use /dev/hwrng to fill the kernel entropy pool, - which is used internally and exported by the /dev/urandom and - /dev/random special files. - -Theory of operation: - - CHARACTER DEVICE. Using the standard open() - and read() system calls, you can read random data from - the hardware RNG device. This data is NOT CHECKED by any - fitness tests, and could potentially be bogus (if the - hardware is faulty or has been tampered with). Data is only - output if the hardware "has-data" flag is set, but nevertheless - a security-conscious person would run fitness tests on the - data before assuming it is truly random. - - The rng-tools package uses such tests in "rngd", and lets you - run them by hand with a "rngtest" utility. - - /dev/hwrng is char device major 10, minor 183. - - CLASS DEVICE. There is a /sys/class/misc/hw_random node with - two unique attributes, "rng_available" and "rng_current". The - "rng_available" attribute lists the hardware-specific drivers - available, while "rng_current" lists the one which is currently - connected to /dev/hwrng. If your system has more than one - RNG available, you may change the one used by writing a name from - the list in "rng_available" into "rng_current". +========================================================== +Linux support for random number generator in i8xx chipsets +========================================================== + +Introduction +============ + +The hw_random framework is software that makes use of a +special hardware feature on your CPU or motherboard, +a Random Number Generator (RNG). The software has two parts: +a core providing the /dev/hwrng character device and its +sysfs support, plus a hardware-specific driver that plugs +into that core. + +To make the most effective use of these mechanisms, you +should download the support software as well. Download the +latest version of the "rng-tools" package from the +hw_random driver's official Web site: + + http://sourceforge.net/projects/gkernel/ + +Those tools use /dev/hwrng to fill the kernel entropy pool, +which is used internally and exported by the /dev/urandom and +/dev/random special files. + +Theory of operation +=================== + +CHARACTER DEVICE. Using the standard open() +and read() system calls, you can read random data from +the hardware RNG device. This data is NOT CHECKED by any +fitness tests, and could potentially be bogus (if the +hardware is faulty or has been tampered with). Data is only +output if the hardware "has-data" flag is set, but nevertheless +a security-conscious person would run fitness tests on the +data before assuming it is truly random. + +The rng-tools package uses such tests in "rngd", and lets you +run them by hand with a "rngtest" utility. + +/dev/hwrng is char device major 10, minor 183. + +CLASS DEVICE. There is a /sys/class/misc/hw_random node with +two unique attributes, "rng_available" and "rng_current". The +"rng_available" attribute lists the hardware-specific drivers +available, while "rng_current" lists the one which is currently +connected to /dev/hwrng. If your system has more than one +RNG available, you may change the one used by writing a name from +the list in "rng_available" into "rng_current". ========================================================================== - Hardware driver for Intel/AMD/VIA Random Number Generators (RNG) - Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com> - Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> +Hardware driver for Intel/AMD/VIA Random Number Generators (RNG) + - Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com> + - Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> -About the Intel RNG hardware, from the firmware hub datasheet: - The Firmware Hub integrates a Random Number Generator (RNG) - using thermal noise generated from inherently random quantum - mechanical properties of silicon. When not generating new random - bits the RNG circuitry will enter a low power state. Intel will - provide a binary software driver to give third party software - access to our RNG for use as a security feature. At this time, - the RNG is only to be used with a system in an OS-present state. +About the Intel RNG hardware, from the firmware hub datasheet +============================================================= -Intel RNG Driver notes: +The Firmware Hub integrates a Random Number Generator (RNG) +using thermal noise generated from inherently random quantum +mechanical properties of silicon. When not generating new random +bits the RNG circuitry will enter a low power state. Intel will +provide a binary software driver to give third party software +access to our RNG for use as a security feature. At this time, +the RNG is only to be used with a system in an OS-present state. - * FIXME: support poll(2) +Intel RNG Driver notes +====================== - NOTE: request_mem_region was removed, for three reasons: - 1) Only one RNG is supported by this driver, 2) The location - used by the RNG is a fixed location in MMIO-addressable memory, +FIXME: support poll(2) + +.. note:: + + request_mem_region was removed, for three reasons: + + 1) Only one RNG is supported by this driver; + 2) The location used by the RNG is a fixed location in + MMIO-addressable memory; 3) users with properly working BIOS e820 handling will always - have the region in which the RNG is located reserved, so - request_mem_region calls always fail for proper setups. - However, for people who use mem=XX, BIOS e820 information is - -not- in /proc/iomem, and request_mem_region(RNG_ADDR) can - succeed. + have the region in which the RNG is located reserved, so + request_mem_region calls always fail for proper setups. + However, for people who use mem=XX, BIOS e820 information is + **not** in /proc/iomem, and request_mem_region(RNG_ADDR) can + succeed. -Driver details: +Driver details +============== - Based on: +Based on: Intel 82802AB/82802AC Firmware Hub (FWH) Datasheet - May 1999 Order Number: 290658-002 R + May 1999 Order Number: 290658-002 R - Intel 82802 Firmware Hub: Random Number Generator +Intel 82802 Firmware Hub: + Random Number Generator Programmer's Reference Manual - December 1999 Order Number: 298029-001 R + December 1999 Order Number: 298029-001 R - Intel 82802 Firmware HUB Random Number Generator Driver +Intel 82802 Firmware HUB Random Number Generator Driver Copyright (c) 2000 Matt Sottek <msottek@quiknet.com> - Special thanks to Matt Sottek. I did the "guts", he - did the "brains" and all the testing. +Special thanks to Matt Sottek. I did the "guts", he +did the "brains" and all the testing. |