Random number generator on rpi

[Ulrich Grey]

Hello,

I have tested it on RPI-B and it shows up in dmesg.

KDB: debugger backends: ddb
KDB: current backend: ddb
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FreeBSD 11.0-ALPHA2 #0 r301458M: Mon Jun  6 09:01:49 UTC 2016
    root at wqtest:/usr/obj/usr/src/sys/RPI-B arm
FreeBSD clang version 3.8.0 (tags/RELEASE_380/final 262564) (based on LLVM 3.8.0)
VT: init without driver.
sema_sysinit
CPU: ARM1176JZ-S rev 7 (ARM11J core)
 Supported features: ARM_ISA THUMB2 JAZELLE ARMv4 Security_Ext
 WB enabled LABT branch prediction disabled
  16KB/32B 4-way instruction cache
  16KB/32B 4-way write-back-locking-C data cache
real memory  = 503312384 (479 MB)
avail memory = 481800192 (459 MB)
random: entropy device external interface
kbd0 at kbdmux0
ofwbus0: <Open Firmware Device Tree>
simplebus0: <Flattened device tree simple bus> mem 0x20000000-0x20ffffff on ofwbus0
cpulist0: <Open Firmware CPU Group> on ofwbus0
cpu0: <Open Firmware CPU> on cpulist0
bcm2835_cpufreq0: <CPU Frequency Control> on cpu0
intc0: <BCM2835 Interrupt Controller> mem 0xb200-0xb3ff on simplebus0
bcmrng0: <BCM2708/2835 random number generator> mem 0x104000-0x10400f on simplebus0
systimer0: <BCM2835 System Timer> mem 0x3000-0x3fff on simplebus0
Event timer "BCM2835-3" frequency 1000000 Hz quality 1000
Timecounter "BCM2835-3" frequency 1000000 Hz quality 1000
bcmwd0: <BCM2708/2835 Watchdog> mem 0x10001c-0x100027 on simplebus0
gpio0: <BCM2708/2835 GPIO controller> mem 0x200000-0x2000af on simplebus0
 ...
----------------------------------------
On Mon, 6 Jun 2016 12:49:27 +0800
Jia-Shiun Li <jiashiun at gmail.com> wrote:

> Hi all,
> 
> I occasionally found that RPi has a mysterious undocumented random number
> generator and Linux has a driver for it. [1]
> 
> Out of curiosity I wrote a simple driver according to the Linux one. It is
> simple enough for me without prior rng knowledge to make it work. Or so it
> appears. Patch is attached.
> 
> (Note you need to have the updated dtb file by copying
> {OBJDIR}/{SRCDIR}/sys/{KERNCONF}/modules/{SRCDIR}/sys/modules/dtb/rpi/rpi{,2}.dtb
> to your /boot/msdos)
> 
> Once booted the kernel will output the following line indicating it is
> working:
> 
> bcmrng0: <BCM2708/2835 random number generator> mem 0x104000-0x10400f on
> simplebus0
> 
> I only tested it on RPi2. Guess it will work fine on RPi too.
> 
> I tried to compile rndtest(4) together into the kernel, and it did not
> output or complain about anything. According to the man page this should
> mean the rng works fine, right? Or is there any other tools to verify the
> quality of a rng?
> 
> 
> [1]:
> http://scruss.com/blog/2013/06/07/well-that-was-unexpected-the-raspberry-pis-hardware-random-number-generator/
> 
> -Jia-Shiun.