On 06/18/2013 10:18 AM, Felipe Balbi wrote: > 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. But that is perfectly fine *when* the driver is supported on those archs only. And come on, how much often will this "every now and again" happen? We don't have that much cases where a driver is augmented to work on another arch or platform. It either works on all of them => doesn't need COMPILE_TEST, or work on one or two arches at most. -- js suse labs -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
