Hi, On Tue, Jun 18, 2013 at 06:51:32AM +0200, Michal Marek wrote: > Dne 17.6.2013 22:05, Jiri Slaby napsal(a): > > On 05/23/2013 05:09 AM, Jeff Mahoney wrote: > >> On 5/22/13 10:23 PM, Greg Kroah-Hartman wrote: > >>> On Wed, May 22, 2013 at 11:18:46AM +0200, Jiri Slaby wrote: > >>>> Some drivers can be built on more platforms than they run on. This > >>>> causes users and distributors packaging burden when they have to > >>>> manually deselect some drivers from their allmodconfigs. Or sometimes > >>>> it is even impossible to disable the drivers without patching the > >>>> kernel. > >>>> > >>>> Introduce a new config option COMPILE_TEST and make all those drivers > >>>> to depend on the platform they run on, or on the COMPILE_TEST option. > >>>> Now, when users/distributors choose COMPILE_TEST=n they will not have > >>>> the drivers in their allmodconfig setups, but developers still can > >>>> compile-test them with COMPILE_TEST=y. > >>> > >>> I understand the urge, and it's getting hard for distros to handle these > >>> drivers that just don't work on other architectures, but it's really > >>> valuable to ensure that they build properly, for those of us that don't > >>> have many/any cross compilers set up. > > > > But this is exactly what COMPILE_TEST will give us when set to "y", or > > am I missing something? > > > >>>> Now the drivers where we use this new option: > >>>> * PTP_1588_CLOCK_PCH: The PCH EG20T is only compatible with Intel Atom > >>>> processors so it should depend on x86. > >>>> * FB_GEODE: Geode is 32-bit only so only enable it for X86_32. > >>>> * USB_CHIPIDEA_IMX: The OF_DEVICE dependency will be met on powerpc > >>>> systems -- which do not actually support the hardware via that > >>>> method. > >>> > >>> This seems ripe to start to get really messy, really quickly. Shouldn't > >>> "default configs" handle if this "should" be enabled for a platform or > >>> not, and let the rest of us just build them with no problems? > >> > >> If every time a new Kconfig option is added, corresponding default > >> config updates come with it, sure. I just don't see that happening, > >> especially when it can be done much more clearly in the Kconfig while > >> the developer is writing the driver. > >> > >>> What problems is this causing you? Are you running out of space in > >>> kernel packages with drivers that will never be actually used? > >> > >> Wasted build resources. Wasted disk space on /every/ system the kernel > >> package is installed on. We're all trying to pare down the kernel > >> packages to eliminate wasted space and doing it manually means a bunch > >> of research, sometimes with incorrect assumptions about the results, > >> needs to be done by someone not usually associated with that code. That > >> research gets repeated by people maintaining kernel packages for pretty > >> much every distro. > > > > I second all the above. > > > >>>> +config COMPILE_TEST > >>>> + bool "Compile also drivers which will not load" if EXPERT > >>> > >>> EXPERT is getting to be the "let's hide it here" option, isn't it... > >>> > >>> I don't know, if no one else strongly objects, I can be convinced that > >>> this is needed, but so far, I don't see why it really is, or what this > >>> is going to help with. > >> > >> I'm not convinced adding a || COMPILE_TEST option to every driver that > >> may be arch specific is the best way to go either. Perhaps adding a new > >> Kconfig verb called "archdepends on" or something that will evaluate as > >> true if COMPILE_TEST is enabled but will evaluate the conditional if > >> not. *waves hands* > > > > Sam Ravnborg (the kconfig ex-maintainer) once wrote that he doesn't want > > to extend the kconfig language for this purpose (which I support). That > > a config option is fine and sufficient in this case [1]. Except he > > called the config option "SHOW_ALL_DRIVERS". Adding the current > > maintainer to CCs ;). > > I agree with Sam. 'depends on XY || COMPILE_TEST' is quite > self-explanatory. And even if it's not, you can look up the help text > for COMPILE_TEST. With "archdepends on" or "available on", you need to > know what to look for to override the dependency. you will still end up with: depends on (ARCH_OMAP || ARCH_EXYNOS || ARCH_DAVINCI || ARCH_PPC || ...) And every now and again that particular line will be updated to add another arch dependency. -- balbi
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