Re: [v3 PATCH] crypto: lib/Kconfig - Hide arch options from user

Herbert Xu
2025-02-27T08:43:48Z

On Thu, Feb 27, 2025 at 09:32:51AM +0100, Arnd Bergmann wrote:
>
> This looks like a good approach. Once it works correctly,
> it should be possible to clean up the 'select' statements
> in wireguard as well and just 'select CRYPTO_LIB_CHACHA' etc.

Yes that's the idea.

> I think the more common style is to put the 'default'
> lines before 'select'.

It is the customary place in the crypto tree.

> It appears that the two above are missing a
> 'depends on KERNEL_MODE_NEON' line. There is still
> a runtime check that prevents it from being used on
> non-neon machines, but I think you should add these
> lines here since it's no longer possible to turn
> them off individually when building a kernel for a
> non-NEON target.

Good catch. But I think this was deliberate as it also includes
a non-NEON implementation:

commit b36d8c09e710c71f6a9690b6586fea2d1c9e1e27
Author: Ard Biesheuvel <ardb@kernel.org>
Date: Fri Nov 8 13:22:14 2019 +0100

crypto: arm/chacha - remove dependency on generic ChaCha driver

Instead of falling back to the generic ChaCha skcipher driver for
non-SIMD cases, use a fast scalar implementation for ARM authored
by Eric Biggers. This removes the module dependency on chacha-generic
altogether, which also simplifies things when we expose the ChaCha
library interface from this module.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

> I'm not sure why we need the extra "_INTERNAL" symbols, but I
> may be missing something here. What problem does this solve
> for you?

Without them Kconfig will bomb out because of a loop centering
on CONFIG_CRYPTO.

Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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