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

[Marek Vasut]

On 10/14/24 12:32 PM, Dragan Simic wrote:
> Hello,
> 
> On 2024-10-14 12:26, Alex ThreeD wrote:
>> On Mon, Oct 14, 2024 at 12:10 AM Marek Vasut <marex at denx.de> wrote:
>>> Let's make this override-able via environment variable, because this
>>> might be growing in the future again. Does this work ?
>>>
>>> size_t len = env_get_ulong("kaslrseed_size", 10, 32);
>>
>> Maybe `env_get_hex("rng_seed_size", 32)` would be better? As most 
>> other env are
>> hexadecimal.
>>
>> Actually it seems that entropy required to init pool early has 
>> decreased in
>> Linux 5.19 from 64 bytes (2 * CHACHA_KEY_SIZE) to 32 bytes
>> (BLAKE2S_HASH_SIZE)
>> https://elixir.bootlin.com/linux/v5.18/source/drivers/char/random.c#L236
>> https://elixir.bootlin.com/linux/v5.19/source/drivers/char/random.c#L551
>> Anyway config knob should not harm.
> 
> I think that the value received from the new environment variable
> should be accepted only if it's greater than some hardcoded value,
> in this case 32.  That way, someone won't be able to misconfigure
> their board environment and cause the early random pool initialization
> to be postponed.

Using low number could be useful for testing. Print a WARNING if the 
number is too low perhaps ?