[KJ] centralizing arch-specific kernel config settings

[KJ] centralizing arch-specific kernel config settings

[Robert P. J. Day]

  i noticed just yesterday the apparent redundancy in duplicating
arch-related kernel config settings across a number of Kconfig files,
as in:

$ grep "config GENERIC_BUG" $(find . -name Kconfig)
./arch/x86_64/Kconfig:config GENERIC_BUG
./arch/i386/Kconfig:config GENERIC_BUG
./arch/ppc/Kconfig:config GENERIC_BUG
./arch/um/Kconfig:config GENERIC_BUG
./arch/parisc/Kconfig:config GENERIC_BUG
./arch/powerpc/Kconfig:config GENERIC_BUG
$

in all of the above cases, the Kconfig directive looks like:

...
config GENERIC_BUG
        bool
        default y
        depends on BUG
...

so the obvious purpose is to define the config setting GENERIC_BUG for
a specific and relevant subset of the supported architectures.  but
isn't this a bit silly and overly verbose?  something like this could
just as easily (and more cleanly) be done using something like this in
init/Kconfig:

...
config AUDITSYSCALL
        bool "Enable system-call auditing support"
        depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
        default y if SECURITY_SELINUX
...

clearly, a single setting in init/Kconfig now defines AUDITSYSCALL for
just the appropriate subset of architectures, rather than spreading
that across multiple arch-specific Kconfig files.  the same technique
is used for UID16 in that same file:

...
config UID16
        bool "Enable 16-bit UID system calls" if EMBEDDED
        depends on ARM || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) ...
...

  is there any reason config settings like GENERIC_BUG can't be
centralized in a single place like that?  i'm *guessing* a pile of
config settings could be simplified like this.

rday

-- 
====================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
====================================
_______________________________________________
Kernel-janitors mailing list
Kernel-janitors@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/kernel-janitors

Re: [KJ] centralizing arch-specific kernel config settings

[Matthew Wilcox]

On Thu, Apr 26, 2007 at 07:06:56AM -0400, Robert P. J. Day wrote:
> in all of the above cases, the Kconfig directive looks like:
> 
> ...
> config GENERIC_BUG
>         bool
>         default y
>         depends on BUG
> ...

It should proably use def_bool y instead of bool, default y.

>   is there any reason config settings like GENERIC_BUG can't be
> centralized in a single place like that?  i'm *guessing* a pile of
> config settings could be simplified like this.

Is it simpler?
_______________________________________________
Kernel-janitors mailing list
Kernel-janitors@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/kernel-janitors

Re: [KJ] centralizing arch-specific kernel config settings

[Robert P. J. Day]

On Thu, 26 Apr 2007, Matthew Wilcox wrote:

> On Thu, Apr 26, 2007 at 07:06:56AM -0400, Robert P. J. Day wrote:
> > in all of the above cases, the Kconfig directive looks like:
> >
> > ...
> > config GENERIC_BUG
> >         bool
> >         default y
> >         depends on BUG
> > ...
>
> It should proably use def_bool y instead of bool, default y.

i agree, but there's a bazillion of the slightly longer form, and i
doubt it's worth trying to change them over (unless someone wants to
take that on as a KJ project and do it an architecture at a time).

> >   is there any reason config settings like GENERIC_BUG can't be
> > centralized in a single place like that?  i'm *guessing* a pile of
> > config settings could be simplified like this.
>
> Is it simpler?

it's definitely shorter, but i'm guessing it's probably *conceptually*
easier for each architecture to look after its own "generic" settings,
even if it's more verbose.  so never mind, it was just a thought.

rday

-- 
====================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
====================================
_______________________________________________
Kernel-janitors mailing list
Kernel-janitors@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/kernel-janitors