Rockchip RK35xx: Low RNG entropy

[ColorfulRhino]

What happened?

The RNG entropy pool on RK3588 (tested with NanoPi R6C) and RK3568 (tested with NanoPi R5C) always stays at 256 bits, which is very low.

In theory, the hardware based RNG generator should be active for RK35xx in the edge kernel. Something is not working as it should.

How to reproduce?

Watch your entropy with cat /proc/sys/kernel/random/entropy_avail or watch -n 1 cat /proc/sys/kernel/random/entropy_avail

Branch

main (main development branch)

On which host OS are you running the build script and observing this problem?

Ubuntu 24.04 Noble

Are you building on Windows WSL2?

• Yes, my Ubuntu/Debian/OtherOS is running on WSL2

Relevant log URL

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[github-actions]

Jira ticket: AR-2388

[ColorfulRhino]

Maybe not a bug?

Resources:

• https://unix.stackexchange.com/a/704743
• https://lore.kernel.org/lkml/20220527084855.501642285@linuxfoundation.org/

[alexl83]

stable at 256 while catting /dev/random on my orangepi5plus running 6.8.12

[sfx2000]

Not a bug, it's per design...

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.19-rc1&id=6e8ec2552c7d13991148e551e3325a624d73fac6

Also see issue 4170, which I opened last year against Jammy

[ColorfulRhino]

Not a bug, it's per design...

Yes, this is what I thought after some research. The commit you linked is the same that I linked above 😄

So everything is well after all.