UF_DoC
Posts: 49
Joined: Wed Jul 01, 2015 9:00 am

Pi Zero W - Entropy Issue?

Sun Mar 31, 2019 9:18 pm

Good Day

I came across a strange issue when using a pi zero and a stock stretch install and apt-get update/upgrade.

I want to run chromium-browser in kiosk mode but I get the below error for quite some time after bootup:

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[email protected]:~ $ chromium-browser
getrandom indicates that the entropy pool has not been initialized. Rather than continue with poor entropy, this process will block until entropy is available
read somewhere that I need to check how much entropy I have using:

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[email protected]:~ $ cat /proc/sys/kernel/random/entropy_avail
49
running the command multiple times showed it increased then went back to zero then increased again but not going over 100.

read somewhere else to install rng-tools:

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sudo apt-get install rng-tools
This immediately fixed the issue with "entropy" now over 2000.

Im curious if this is an issue? or is this expected behaviour? why did I need to install rng-tools?

Thanks

epoch1970
Posts: 4140
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: Pi Zero W - Entropy Issue?

Sun Mar 31, 2019 9:43 pm

https://unix.stackexchange.com/a/387175

If the Pi runs headless it misses most of the linux default entropy sources.
There is a driver for the random number generator included in the Pi, and rngd can use it.
You fixed your issue, well done. As to why rngd is not installed by default, I'm not sure. A lot of Pis are used headless.
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

Andyroo

Re: Pi Zero W - Entropy Issue?

Mon Apr 01, 2019 12:44 am

epoch1970 wrote:
Sun Mar 31, 2019 9:43 pm
https://unix.stackexchange.com/a/387175

If the Pi runs headless it misses most of the linux default entropy sources.
There is a driver for the random number generator included in the Pi, and rngd can use it.
You fixed your issue, well done. As to why rngd is not installed by default, I'm not sure. A lot of Pis are used headless.
Going by this post it’s being built in. I assume this is Buster and not an update to Stretch.

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