Re: [PATCH v6 02/21] arm64: Allow mismatched 32-bit EL0 support

[Will Deacon]

On Fri, May 21, 2021 at 11:25:23AM +0100, Catalin Marinas wrote:
> On Tue, May 18, 2021 at 10:47:06AM +0100, Will Deacon wrote:
> > +static bool has_32bit_el0(const struct arm64_cpu_capabilities *entry, int scope)
> > +{
> > +	if (!has_cpuid_feature(entry, scope))
> > +		return allow_mismatched_32bit_el0;
> > +
> > +	if (scope == SCOPE_SYSTEM)
> > +		pr_info("detected: 32-bit EL0 Support\n");
> > +
> > +	return true;
> > +}
> 
> We may have discussed this before: AFAICT this will print 32-bit EL0
> detected even if there's no 32-bit EL0 on any CPU. Should we instead
> print 32-bit EL0 detected on CPU X when allow_mismatched_32bit_el0 is
> passed? It would also give us an indication of the system configuration
> when people start reporting bugs.

The function above only runs if we've detected 32-bit support via
aa64pfr0_el1, so I think we're ok. We also have a print when we detect the
mismatch (see enable_mismatched_32bit_el0()).

Will