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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
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Adding upstream version 6.1.76.upstream/6.1.76upstream
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+==========================================================
+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>
+
+
+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.
+
+Intel RNG Driver notes
+======================
+
+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.
+
+Driver details
+==============
+
+Based on:
+ Intel 82802AB/82802AC Firmware Hub (FWH) Datasheet
+ May 1999 Order Number: 290658-002 R
+
+Intel 82802 Firmware Hub:
+ Random Number Generator
+ Programmer's Reference Manual
+ December 1999 Order Number: 298029-001 R
+
+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.