Re: [Ksummit-discuss] RFC: Kernel tinification - kernel config reduction

[Guenter Roeck <linux@roeck-us.net>]

On Wed, Aug 13, 2014 at 09:53:58PM +0200, Geert Uytterhoeven wrote:
> On Wed, Aug 13, 2014 at 8:07 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> > Major problem I see is that many architecture maintainers don't seem to care
> > about "make allmodconfig" and/or "make allyesconfig", meaning there is no
> > simple means to at least compile-test all code that _can_ be enabled for
> > a given architecture. And don't even mention "make randconfig".
> 
> There are still architectures that don't support multi-platform kernels, which
> is a requirement for good coverage.
> 
This is not about creating a working kernel, but for compile tests. I have
separate configurations to test working kernels. But I would prefer to build,
say, no more than half a dozen arm configurations instead of the 40 in my
current build list.

> An alternative could be to have several allmodconfig builds, one for each
> subset that can't be built-in together, like
> 
> make CONFIG_SUBSET_FOO=y allmodconfig
> make CONFIG_SUBSET_BAR=y allmodconfig
> ...
> 
Maybe something like 

make PCI=n allmodconfig
make GPIOLIB=n allmodconfig

which would let me disable key options selectively so I can improve compile
coverage without having to go through all configurations (or randconfig).

> > Instead of CONFIG_TINY or similar, I would find it more important to get
> > allmodconfig and/or allyesconfig to work for as many architectures as
> > possible, and to create some means to help catching errors of the
> > kind detected by randconfig, only in a more deterministic way.
> 
> The few allmodconfig/allyesconfig builds on
> kisskb.ellerman.id.au/kisskb/matrix/ are actually not in such a bad shape.
> Shall more be added?
> 
I don't think there are any you could add, at least none which actually build.
arm:allmodconfig was quite useful, but it has been broken since 3.10 or so,
and I don't think it will ever get fixed.

> You also only build some of the allmodconfigs?
> 
Never "only". I always also build defconfig, plus at least sometimes a couple
of additional configurations (if available) to improve coverage of conditional
functionality.

Guenter