What's the meaning of SUBDIRS ?

[Philipp Ittershagen]

make needs to enter the linux source tree in order to read the
top-level Makefile from that directory.

SUBDIRS is a variable used by the kernel top-level Makefile to know
which directory it should build external modules after performing some
initial checks to ensure proper compilation.


Greetings,

Philipp

On Sat, Oct 1, 2011 at 11:53 AM, Parmenides <mobile.parmenides at gmail.com> wrote:
> Hi,
>
>    When making a kernel module outside the kernel source tree, I can
> use this command to make my kernel module:
>
>                                            make -C /usr/src/linux
> SUBDIRS=$PWD modules
>
> According to man, the -C option will chanage the current working
> directory to the top level directory of kernel source tree.
> Furthermore, the SUBDIRS varialbe contains the path of current working
> directory where my module is living. So, why does 'make' need to enter
> /usr/src/linux first? And, What's the role of 'SUBDIRS'? Thanks.
>
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