<div dir="ltr">Generally, <div><br></div><div>obj-y += foo.o </div><div><br></div><div>This tells kbuild that there is one object in that directory, named foo.o. foo.o will be built from foo.c or foo.S.<br></div><div><div>
If foo.o shall be built as a module, the variable obj-m is used.</div></div><div><br></div><div>obj-$(CONFIG_FOO) += foo.o<br></div><div><br></div><div>$(CONFIG_FOO) evaluates to either y (for built-in) or m (for module). If CONFIG_FOO is neither y nor m, then the file will not be compiled nor linked.<br>
</div><div><br></div><div>The #1 in your case, ifdef i.e. if the compilation flag (in your case CONFIG_MY_SYSTEM_CALL) is defined then only the module is included into the image.</div><div><br></div><div>I hope this helps you.</div>
<div><br></div><div>Regards,</div><div>Srinivas G.</div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Jul 31, 2013 at 3:42 PM, Iker Pedrosa <span dir="ltr"><<a href="mailto:ikerpedrosam@gmail.com" target="_blank">ikerpedrosam@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Wed, 24 Jul 2013 17:19:13 +0530<br>
<div class="im">Srinivas Ganji <<a href="mailto:srinivasganji.kernel@gmail.com">srinivasganji.kernel@gmail.com</a>> wrote:<br>
<br>
> Hi Iker Pedrosa,<br>
><br>
</div><div class="im">> Please look at how to write the Kconfig files. We need to write a new<br>
> Kconfig file for our own implementation.<br>
><br>
> Regards,<br>
> Srinivas G.<br>
><br>
><br>
<br>
</div>Hi again,<br>
<br>
I've just created the Kconfig and I have pend it from General setup, it's been a little bit difficult, mainly the part to pend it from General setup. Now, I've got some questions, which is the difference between the following statements?<br>
1)<br>
ifdef CONFIG_MY_SYSTEM_CALL<br>
obj-y += my_system_calls.o<br>
endif<br>
<br>
2)<br>
obj-(CONFIG_MY_SYSTEM_CALL) += my_system_calls.o<br>
<br>
Where do I build the object in the object in the second option? Is it done in the same Makefile or in another one?<br>
<br>
Regards,<br>
<span class="HOEnZb"><font color="#888888">--<br>
Iker Pedrosa <<a href="mailto:ikerpedrosam@gmail.com">ikerpedrosam@gmail.com</a>><br>
</font></span></blockquote></div><br></div>