> -----Original Message----- > From: kernelnewbies-bounces@xxxxxxxxxxxxxxxxx [mailto:kernelnewbies- > bounces@xxxxxxxxxxxxxxxxx] On Behalf Of Robert P. J. Day > Sent: Friday, February 24, 2012 11:41 AM > To: Kernel Newbies > Subject: want to verify equivalence of Kconfig variants > > > i'm fairly sure i know the answer to this, but i figured i'd run it > by others just to make sure i'm not missing anything subtle. > > in drivers/video/omap2/Makefile, we see: > > ... snip ... > obj-$(CONFIG_OMAP2_DSS) += dss/ > obj-$(CONFIG_FB_OMAP2) += omapfb/ > obj-y += displays/ > ... snip ... > > and when i see "obj-y", i like to assume that's a component that will > be compiled unconditionally. but if you look at the Kconfig file in > the displays/ directory, you see: > > menu "OMAP2/3 Display Device Drivers" > depends on OMAP2_DSS > ... entire file contents ... > endmenu > > but that suggests that that entire subdirectory depends on > OMAP2_DSS, so one could remove the dependency from that Kconfig file > and just move it up to the Makefile above: > > obj-$(CONFIG_OMAP2_DSS) += displays/ > > correct? i prefer that approach since the dependency is obvious from > the Makefile, without having to descend into the directory itself to > learn of it. > > thoughts? is there anything i'm not noticing about this? > > rday I'm no expert on kbuild, but I don't think your modification would be equivalent to what's there now. In Documentation/kbuild/makefiles.txt, they describe what obj-y means in section 3.2. If I follow the description, it defines objects that will be linked with the kernel image, so this: obj-y += displays/ presumably means that all source files in the displays subdirectory will be compiled and linked with the kernel image. With this: obj-$(CONFIG_OMAP2_DSS) += displays/ CONFIG_OMAP2_DSS could evaluate to 'm' depending on your configuration, which would mean the same objects would be linked into a loadable module. Jeff Haran _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
