Re: [PATCH] hw/arm/virt: dt: add rng-seed property

[Jason A. Donenfeld]

On 6/27/22, Peter Maydell <peter.maydell@linaro.org> wrote:
> On Mon, 27 Jun 2022 at 17:07, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>>
>> In 60592cfed2 ("hw/arm/virt: dt: add kaslr-seed property"), the
>> kaslr-seed property was added, but the equally as important rng-seed
>> property was forgotten about, which has identical semantics for a
>> similar purpose. This commit implements it in exactly the same way as
>> kaslr-seed.
>
> Not an objection, since if this is what the dtb spec says we need
> to provide then I guess we need to provide it, but:
> Why do we need to give the kernel two separate random seeds?
> Isn't one sufficient for the kernel to seed its RNG and generate
> whatever randomness it needs for whatever purposes it wants it?
>

Seems a bit silly to me too. `rng-seed` alone ought to be sufficient.
After the kernel calls add_bootloader_randomness() on it,
get_random_long() can be used for kaslr'ing and everything else too.
So I'm not sure what's up, but here we are. Maybe down the line I'll
look into the details and formulate a plan to remove `kaslr-seed` if
my supposition is correct.

Jason