[PATCH v3 7/8] riscv: Add parameter for skipping access speed tests

[Geert Uytterhoeven]

Hi Andrew,

On Tue, 8 Apr 2025 at 15:03, Andrew Jones <ajones at ventanamicro.com> wrote:
> On Tue, Apr 08, 2025 at 02:25:12PM +0200, Geert Uytterhoeven wrote:
> > On Tue, 4 Mar 2025 at 13:02, Andrew Jones <ajones at ventanamicro.com> wrote:
> > > Allow skipping scalar and vector unaligned access speed tests. This
> > > is useful for testing alternative code paths and to skip the tests in
> > > environments where they run too slowly. All CPUs must have the same
> > > unaligned access speed.
> > >
> > > The code movement is because we now need the scalar cpu hotplug
> > > callback to always run, so we need to bring it and its supporting
> > > functions out of CONFIG_RISCV_PROBE_UNALIGNED_ACCESS.
> > >
> > > Signed-off-by: Andrew Jones <ajones at ventanamicro.com>
> >
> > > --- a/arch/riscv/kernel/unaligned_access_speed.c
> > > +++ b/arch/riscv/kernel/unaligned_access_speed.c
> >
> > >  static int __init check_unaligned_access_all_cpus(void)
> > >  {
> > >         int cpu;
> > >
> > > -       if (!check_unaligned_access_emulated_all_cpus())
> > > +       if (unaligned_scalar_speed_param == RISCV_HWPROBE_MISALIGNED_SCALAR_UNKNOWN &&
> > > +           !check_unaligned_access_emulated_all_cpus()) {
> > >                 check_unaligned_access_speed_all_cpus();
> > > -
> > > -       if (!has_vector()) {
> > > +       } else {
> > > +               pr_info("scalar unaligned access speed set to '%s' by command line\n",
> > > +                       speed_str[unaligned_scalar_speed_param]);
> > >                 for_each_online_cpu(cpu)
> > > -                       per_cpu(vector_misaligned_access, cpu) = RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED;
> > > -       } else if (!check_vector_unaligned_access_emulated_all_cpus() &&
> > > -                  IS_ENABLED(CONFIG_RISCV_PROBE_VECTOR_UNALIGNED_ACCESS)) {
> > > +                       per_cpu(misaligned_access_speed, cpu) = unaligned_scalar_speed_param;
> > > +       }
> > > +
> > > +       if (!has_vector())
> > > +               unaligned_vector_speed_param = RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED;
> > > +
> > > +       if (unaligned_vector_speed_param == RISCV_HWPROBE_MISALIGNED_VECTOR_UNKNOWN &&
> > > +           !check_vector_unaligned_access_emulated_all_cpus() &&
> > > +           IS_ENABLED(CONFIG_RISCV_PROBE_VECTOR_UNALIGNED_ACCESS)) {
> > >                 kthread_run(vec_check_unaligned_access_speed_all_cpus,
> > >                             NULL, "vec_check_unaligned_access_speed_all_cpus");
> > > +       } else {
> > > +               pr_info("vector unaligned access speed set to '%s' by command line\n",
> > > +                       speed_str[unaligned_vector_speed_param]);
> >
> > On SiPEED MAiXBiT, unaligned_scalar_speed_param is zero, and it prints:
> >
> >     scalar unaligned access speed set to '(null)' by command line
>
> Thanks, Geert. I think unaligned_scalar_speed_param is likely 1 in this
> case and we should be printing 'emulated', but I neglected to add that
> string to speed_str[].

No, the value of unaligned_scalar_speed_param is zero.

> I'll fix this too.

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds