Dne 19.2.2015 v 15:53 Arnd Bergmann napsal(a): > On Thursday 19 February 2015 13:11:07 Michal Marek wrote: >> On 2015-02-18 18:12, Arnd Bergmann wrote: >>> In the media drivers, the v4l2 core knows about all submodules >>> and calls into them from a common function. However this cannot >>> work if the modules that get called are loadable and the >>> core is built-in. In that case we get >>> >>> drivers/built-in.o: In function `set_type': >>> drivers/media/v4l2-core/tuner-core.c:301: undefined reference to `tea5767_attach' >>> drivers/media/v4l2-core/tuner-core.c:307: undefined reference to `tea5761_attach' >>> drivers/media/v4l2-core/tuner-core.c:349: undefined reference to `tda9887_attach' >>> drivers/media/v4l2-core/tuner-core.c:405: undefined reference to `xc4000_attach' >>> [...] >>> Ideally Kconfig would be used to avoid the case of a broken dependency, >>> or the code restructured in a way to turn around the dependency, but either >>> way would require much larger changes here. >> >> What can be done without extending kbuild is to accept >> CONFIG_VIDEO_TUNER=y and CONFIG_MEDIA_TUNER_FOO=m, but build both into >> the kernel, e.g. > > Right, but > >> diff --git a/drivers/media/tuners/Kconfig b/drivers/media/tuners/Kconfig >> index 42e5a01..d2c7e89 100644 >> --- a/drivers/media/tuners/Kconfig >> +++ b/drivers/media/tuners/Kconfig >> @@ -71,6 +71,11 @@ config MEDIA_TUNER_TEA5767 >> help >> Say Y here to include support for the Philips TEA5767 radio tuner. >> >> +config MEDIA_TUNER_TEA5767_BUILD >> + tristate >> + default VIDEO_TUNER || MEDIA_TUNER_TEA5767 >> + depends on MEDIA_TUNER_TEA5767!=n >> + >> config MEDIA_TUNER_MSI001 >> tristate "Mirics MSi001" >> depends on MEDIA_SUPPORT && SPI && VIDEO_V4L2 > > We'd then have to do the same for each tuner driver that we have in the > kernel or that gets added later. Yes :-(. >> Actually, I have hard time coming up with a kconfig syntactic sugar to >> express such dependency. If I understand it correctly, the valid >> configurations in this case are >> >> MEDIA_TUNER_TEA5767 n m y >> VIDEO_TUNER n x x x >> m x x x >> y x x >> >> I.e. only VIDEO_TUNER=y and MEDIA_TUNER_TEA5767=m is incorrect, isn't >> it? > > Yes, I think that is correct. OK. In this case, a kconfig extension would be really too specific: "if set, set to at least X but only if X is set as well." > We have similar problems in other areas > of the kernel. In theory, we could enforce the VIDEO_TUNER driver to > be modular here by adding lots of dependencies to it: > > config VIDEO_TUNER > tristate > depends on MEDIA_TUNER_TEA5761 || !MEDIA_TUNER_TEA5761 > depends on MEDIA_TUNER_TEA5767 || !MEDIA_TUNER_TEA5767 > depends on MEDIA_TUNER_MSI001 || !MEDIA_TUNER_MSI001 Nah, that's even uglier. I suggest to merge your IS_REACHABLE patch. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
