Re: Weak x86 aliases

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 28/12/2018 à 14:57, Cherry G.Mathew a écrit :
> Maxime Villard <max%m00nbsd.net@localhost> writes:
> > > Introduce a weak alias method of exporting different implementations
> > > of the same API.
> >
> > Please revert or fix this change.
>
> I'm not sure what the fix is - do you have a suggestion ?

either re-apply it without using weak symbols, or change the modloader
to accept weak symbols

> > The kernel modules that use these functions can't be modloaded
> > anymore, because weak symbols aren't resolved.
> >
> > Eg, NVMM can't be modloaded anymore, because it uses rcr0 among others.
>
> I think I'll revert these for now, because PVHVM doesn't/shouldn't use
> them anyway, but I'd like to know how to fix this properly. modload not
> working due to __weak_alias() sounds like something we don't do properly
> in the modload path.

There is a check in kobj_sym_lookup():

926 	case STB_WEAK:
927 		kobj_error(ko, "weak symbols not supported");
928 		return EINVAL;

To resolve correctly I guess we need to take the strongest of the
duplicated symbols.