Re: [PATCH v2] rockchip: board: Increase rng-seed size to make it sufficient for modern Linux

[Dragan Simic <dsimic@manjaro.org>]

On 2024-10-14 20:50, Alex ThreeD wrote:
> On Mon, Oct 14, 2024 at 9:19 PM Dragan Simic <dsimic@manjaro.org> 
> wrote:
>> > +             // rng_seed_size should be 32 bytes for Linux 5.19+, or 64 for older
>> > Linux'es
>> 
>> Shouldn't it be 8 for older kernels?
> 
> Looking into source code I would say Linux 5.17 requires 64 bytes to 
> init crng.
> 8 bytes rng_seed should help somehow, but It will not init crng 
> instantly.
> Maybe some even Linux required only 8 bytes but I doubt so.
> 8 bytes was too small for cryptographic PRNG yet 20 years ago.

To sum up the replies from Marek, the lower limit should be 64.

>> 
>> > +             log_warning("Too small rng_seed_size (%lu). It is likely
>> > insufficient to init linux crng\n",
>> > +                         len);
>> 
>> Perhaps this would read better:
>> 
>>    "Value for rng_seed_size too low (%lu) and likely insufficient
>>    for the Linux RNG initialization"
> 
> Thanks, I will apply It in v3.

Great, thanks!