Hi Rob, On Wed, Apr 13, 2022 at 4:32 PM Rob Herring <robh@xxxxxxxxxx> wrote: > 'does not have a usable get_cycles(), ...' as clearly some arches have > get_cycles() and yet still need a fallback. > > Why not handle the 'if get_cycles() returns 0 do the fallback' within > a weak random_get_entropy() function? Then more arches don't need any > random_get_entropy() implementation. No, this doesn't really work. Actually, most archs don't need a random_get_entropy() function, because it exists in asm-generic doing the thing we want. So that's taken care of. But weak functions as you suggested would be quite suboptimal, because on, e.g. x86, what we have now gets inlined into a single rdtsc instruction. Also, the relation between get_cycles() and random_get_entropy() doesn't always hold; some archs may not have a working get_cycles() function but do have a path for a random_get_entropy(). Etc, etc. So I'm pretty sure that this commit is really the most simple and optimal thing to do. I really don't want to go the weak functions route. Jason
