Ccing kbuild fellows (see the very bottom). On 03/24/2015, 06:15 PM, David Herrmann wrote: > Hi > > On Tue, Mar 24, 2015 at 5:46 PM, Jiri Slaby <jslaby@xxxxxxx> wrote: >> On 03/09/2015, 02:09 PM, Greg Kroah-Hartman wrote: >>> --- /dev/null >>> +++ b/samples/kdbus/Makefile >>> @@ -0,0 +1,10 @@ >>> +# kbuild trick to avoid linker error. Can be omitted if a module is built. >>> +obj- := dummy.o >>> + >>> +hostprogs-y += kdbus-workers >>> + >>> +always := $(hostprogs-y) >> >> Errr, no. Not only it causes build failures (even with KDBUS=n), it >> definitely should not be built for everyone. > > It's only built if CONFIG_SAMPLES is set, right? Yes, but I build other samples selected with separate CONFIG_ options like CONFIG_SAMPLE_LIVEPATCH. So this guy should have its own CONFIG_ option too, because I (and likely others) don't want to build it. All of the samples should be protected at least by their respective kernel CONFIG_ option IMO. > What build-failures does it cause? linux/kdbus.h is not optional based > on CONFIG_KDBUS, so the samples should build just fine. Can you tell > me what kind of errors you get? The kbuild-robots didn't report > anything so far. The output is this: In file included from samples/kdbus/kdbus-workers.c:79:0: /home/latest/linux/samples/kdbus/kdbus-api.h:5:25: fatal error: linux/kdbus.h: No such file or directory #include <linux/kdbus.h> ^ compilation terminated. I now know that I have to install_headers *if* I want to build the sample. But I don't want to build it in the first place. (So the config option above should be all we need.) >> And why is it a host prog? It's a sample prog for the kernel I am >> building, i.e. for the destination arch, like all the other samples. > > It's modeled after the other user-space examples in ./samples/, which > all use hostprogs (see samples/{bpf,hidraw,seccomp,uhid}/Makefile). I > have no idea how to build programs that run on the target > architecture. Documentation/kbuild/makefiles.txt doesn't list it, > which is, I guess, the reason why everyone used hostprogs so far. And > given that autotools calls the target architecture "--host", I > actually thought this is what hostprogs does.. apparently that's not > the case, sorry. Oh, it's cut&paste, I see. This does not look correct though. The hack inclusive. Host progs are intended to be run on the host where the kernel is built. During the compilation or such (like x/menuconfig). Quite misleading naming if you are used to the autotools one. thanks, -- js suse labs -- 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