Re: [PATCH v2 1/3] x86/cpufeatures: Add {required,disabled} feature configs

[Xin Li]

On 6/21/2024 10:32 AM, Borislav Petkov wrote:
> On Sun, Jun 16, 2024 at 01:57:41AM -0700, Xin Li (Intel) wrote:
> > diff --git a/arch/x86/Kconfig.cpufeatures b/arch/x86/Kconfig.cpufeatures
> > new file mode 100644
> > index 000000000000..5ed24e45df87
> > --- /dev/null
> > +++ b/arch/x86/Kconfig.cpufeatures
> > @@ -0,0 +1,197 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +#
> > +# x86 feature bits (see arch/x86/include/asm/cpufeatures.h) that are
> > +# either REQUIRED to be enabled, or DISABLED (always ignored) for this
> > +# particular compile-time configuration.  The tests for these features
> > +# are turned into compile-time constants via the generated
> > +# <asm/featuremasks.h>.
> > +#
> > +# The naming of these variables *must* match asm/cpufeatures.h, e.g.,
> > +#     X86_FEATURE_ALWAYS <==> X86_REQUIRED_FEATURE_ALWAYS
> > +#     X86_FEATURE_FRED   <==> X86_DISABLED_FEATURE_FRED
> > +#
> > +# And these REQUIRED and DISABLED config options are manipulated in an
> > +# AWK script as the following example:
> > +#
> > +#                          +----------------------+
> > +#                          |    X86_FRED = y ?    |
> > +#                          +----------------------+
> > +#                              /             \
> > +#                           Y /               \ N
> > +#  +-------------------------------------+   +-------------------------------+
> > +#  | X86_DISABLED_FEATURE_FRED undefined |   | X86_DISABLED_FEATURE_FRED = y |
> > +#  +-------------------------------------+   +-------------------------------+
> > +#                                                        |
> > +#                                                        |
> > +#     +-------------------------------------------+      |
> > +#     | X86_FEATURE_FRED: feature word 12, bit 17 | ---->|
> > +#     +-------------------------------------------+      |
> > +#                                                        |
> > +#                                                        |
> > +#                                     +-------------------------------+
> > +#                                     | set bit 17 of DISABLED_MASK12 |
> > +#                                     +-------------------------------+
> > +#
>
> Look ma, a picture. :-)
>
> But yeah, this is better.

We are better in intercepting pictures :)

Thanks!
    Xin