Re: Can KEY_DH_OPERATIONS become tristate? (was: Re: Kernel 5.3.0 stuck during boot on Amiga)

[David Howells]

Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:

> > > TL;DR: CONFIG_CRYPTO_DH=y is reported to cause boot delays of several
> > > minutes on old and slow machines.
> >
> > Why is it doing that?  It doesn't do anything unless it is called, so
> > something must be calling it.
>
> I don't know.  Enabling initcall_debug shows that dh_init() takes a very long
> time.

Ah...  The bit that handles keyctl_dh_compute() doesn't do anything unless
asked, but the bit in the crypto layer that does dh does (ie. dh_init()).  I
guess it's doing some sort of self-test, but I can't see how it effects that.
I think you need to consult the author/maintainer of crypto/dh.c.

It might be possible to make CONFIG_KEY_DH_OPERATIONS not depend on
CONFIG_CRYPTO_DH and have crypto_alloc_kpp() load the *crypto* part on
demand.  Failing that, I can look into demand-loading keyctl operations.

David