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

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Date:   Wed, 14 Jun 2023 07:01:04 -0500
From:   Eric DeVolder <eric.devolder@...cle.com>
To:     Kees Cook <keescook@...omium.org>
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Subject: Re: [PATCH v1 00/21] refactor Kconfig to consolidate KEXEC and CRASH
 options



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?

Thank you!
eric

> -Kees
>