On Wed, 2015-04-22 at 20:20 +0200, Denys Vlasenko wrote: > Kernel has a growing number of CONFIG items which are not > user-selectable features of their particular kernel builds, > but simply booleans controlled by other CONFIGs. > Example: > > config X86 > def_bool y > select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI > select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS > select ARCH_HAS_FAST_MULTIPLIER > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_MIGHT_HAVE_PC_PARPORT > select ARCH_MIGHT_HAVE_PC_SERIO > select HAVE_AOUT if X86_32 > select HAVE_UNSTABLE_SCHED_CLOCK > select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 > select ARCH_SUPPORTS_INT128 if X86_64 > select HAVE_IDE > select HAVE_OPROFILE > ... > > I see how this practice originated: "select" statement > was initially added so that if feature X requires feature Y, > this can be enforced, but it was easy to use it to define > other booleans. > > I have a feeling that in retrospect, it was a mistake. > > It clutters .config with information which has nothing to do > with user's choice.
No, those selects fill the .config with values as a direct consequence of the choices made by the person doing the configuration. You might just as well consider those values things that the user wanted to have too. > More importantly, now when you read some code, you don't know > whether a CONFIG_FOO you look at is user's configuration choice > or something else. So what? > Now there are hundreds, maybe even thousands of these non-config > CONFIGs everywhere. > > The same effect can be achieved, with marginally more typing, > with usual C defines in some header file: > > #ifdef CONFIG_X86 > # define ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS > # define ARCH_HAS_FAST_MULTIPLIER > # define ARCH_HAS_GCOV_PROFILE_ALL > # define ARCH_MIGHT_HAVE_PC_PARPORT > # define ARCH_MIGHT_HAVE_PC_SERIO > ... > > Maybe we should stop doing the former and use the latter method? And lose the sanity checks that the kconfig tools provide? And the benefit of a having a single .config file showing the configuration the build will (or did) use? Anyhow, -ENOPATCH. Because I actually suspect that this scheme will complicate the tree quite a bit. Do send in patches showing how this scheme allows to drop a few Kconfig symbols. That makes it much easier to evaluate the pros and cons of your idea. Thanks, Paul Bolle -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
