Re: [PATCH v1 00/21] refactor Kconfig to consolidate KEXEC and CRASH options

[Eric DeVolder]

On 6/14/23 22:26, Michael Ellerman wrote:
> Eric DeVolder <eric.devolder@xxxxxxxxxx> writes:
> > On 6/13/23 15:21, Kees Cook wrote:
> > > On Mon, Jun 12, 2023 at 01:27:52PM -0400, Eric DeVolder wrote:
> > > > The Kconfig is refactored to consolidate KEXEC and CRASH options from
> > > > various arch/<arch>/Kconfig files into new file kernel/Kconfig.kexec.
> > >
> > > This looks very nice!
> > Thank you Kees!
> >
> > > > [...]
> > > > - The boolean ARCH_HAS_<option> in effect allows the arch to determine
> > > >     when the feature is allowed.  Archs which don't have the feature
> > > >     simply do not provide the corresponding ARCH_HAS_<option>.
> > > >     For each arch, where there previously were KEXEC and/or CRASH
> > > >     options, these have been replaced with the corresponding boolean
> > > >     ARCH_HAS_<option>, and an appropriate def_bool statement.
> > > >
> > > >     For example, if the arch supports KEXEC_FILE, then the
> > > >     ARCH_HAS_KEXEC_FILE simply has a 'def_bool y'. This permits the
> > > >     KEXEC_FILE option to be available.
> > > >
> > > >     If the arch has a 'depends on' statement in its original coding
> > > >     of the option, then that expression becomes part of the def_bool
> > > >     expression. For example, arm64 had:
> > > >
> > > >     config KEXEC
> > > >       depends on PM_SLEEP_SMP
> > > >
> > > >     and in this solution, this converts to:
> > > >
> > > >     config ARCH_HAS_KEXEC
> > > >       def_bool PM_SLEEP_SMP
> > > >
> > > >
> > > > - In order to account for the differences in the config coding for
> > > >     the three common options, the ARCH_SUPPORTS_<option> is used.
> > > >     This options has a 'depends on <option>' statement to couple it
> > > >     to the main option, and from there can insert the differences
> > > >     from the common option and the arch original coding of that option.
> > > >
> > > >     For example, a few archs enable CRYPTO and CRYTPO_SHA256 for
> > > >     KEXEC_FILE. These require a ARCH_SUPPORTS_KEXEC_FILE and
> > > >     'select CRYPTO' and 'select CRYPTO_SHA256' statements.
> > >
> > > Naming nit: "HAS" and "SUPPORTS" feel very similar, and looking at
> > > existing configs, "ARCH_SUPPORTS_..." is already used for doing this
> > > kind of bare "bool" management. e.g. see ARCH_SUPPORTS_INT128
> > >
> > > It looks like you need to split "depends" and "select" so the options
> > > can be chosen separately from the "selectable" configs.
> > >
> > > How about naming this ARCH_SELECTS_<option>, since that's what it's
> > > there for?
> > I'm OK with this. Let's see if others agree?
>
> Yeah please rename one or both of them. At a glance the difference
> between HAS and SUPPORTS is very non-obvious.
>
> I like Kees' suggestion to use ARCH_SUPPORTS and ARCH_SELECTS.
>
> cheers
Michael, ok thanks!
eric