Re: short entropy delay causes RNG hardware error

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Stefano,

On 06.08.24 10:33, Stefano Manni wrote:
> Hello Ahmad,
> 
> On Mon, 2024-08-05 at 18:56 +0200, Ahmad Fatoum wrote:
>>
>> Do you have rngd enabled? You don't need this anymore with a recent
>> enough Linux (>= v6.1 or perhaps earlier).
>>
>> This doesn't fix the underlying issue of course, but it will save you
>> some CPU time.
> 
> Your speculation that rngd is running comes from the error pops every
> 10seconds? I cannot see any systemd service related to rng running on
> my machine. How can I disable it?

Maybe you have haveged running? You could use inotify to see who
is opening the HWRNG's device file.

>> Increasing RTSDCTL_ENT_DLY_MIN to a value appropriate for your board
>> is
>> thus the way to go. I think it would be appropriate to add a device
>> tree
>> property, so the minimum delay value can be set on a per-board basis.
>>
> 
> Got it.

The property would also be appropriate to have in the upstream device
tree bindings, but it's ok to add it to barebox only for now. In that case
use a barebox, prefix though.

Cheers,
Ahmad


> 
> Thank you
> 
> 

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