Hi Mark,

On Wed, Apr 28, 2021 at 2:25 PM Mark Brown [off-list ref] wrote:

The arm64 code allocates an internal constant to every CPU feature it can
detect, distinct from the public hwcap numbers we use to expose some
features to userspace. Currently this is maintained manually which is an
irritating source of conflicts when working on new features, to avoid this
replace the header with a simple text file listing the names we've assigned
and sort it to minimise conflicts.

As part of doing this we also do the Kbuild hookup required to hook up
an arch tools directory and to generate header files in there.

This will result in a renumbering and reordering of the existing constants,
since they are all internal only the values should not be important. The
reordering will impact the order in which some steps in enumeration handle
features but the algorithm is not intended to depend on this and I haven't
seen any issues when testing. Due to the UAO cpucap having been removed in
the past we end up with ARM64_NCAPS being 1 smaller than it was before.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++

I guess the reason you're doing it like this, and not using a simple C
enum, is that some of these definitions are used from asm files?
Do we use similar mechanisms in other places?
Would introducing a generic way to generate headers with definitions
from a C enum be worthwhile?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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

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