CODEWITHSUNDEEP
makefilelinux-kernellinux-device-driverkernel-module
user68293
user68293

Reputation: 63

makefile - what to do with the kconfig file

I stumbled over this site about USB video grabber under Linux, I'm trying to compile the code found here. I have read about makefiles but this one confuses me, cause it's so short:

usbtv-y := usbtv-core.o \
    usbtv-video.o

obj-$(CONFIG_VIDEO_USBTV) += usbtv.o

I wanted to write now my own makefile. What I want to know now is, what the Kconfig file is for and how to use it. I have a hard time finding more information about how to use it, just some stuff regarding KDE which is not what I want. Can someone enlighten me please? I think it's important, cause in the description (on the first site I linked) it says under how to make it work

Linux kernel driver, enable CONFIG_VIDEO_USBTV

Here's the Kconfig file:

config VIDEO_USBTV
        tristate "USBTV007 video capture support"
        depends on VIDEO_V4L2
        select VIDEOBUF2_VMALLOC

        ---help---
          This is a video4linux2 driver for USBTV007 based video capture devices.

          To compile this driver as a module, choose M here: the
          module will be called usbtv

Also, what is meant in the Kconfig file with "choose M here"? Where? How? When?

Upvotes: 3

Views: 6627

Answers (1)

igloo42
igloo42

Reputation: 164

Makefile

This Makefile is not complete. It is included by other makefiles:

This makefile [1] includes this one [2] which includes this one [3] which includes this one [4] which includes this one [5] which includes your example.

Kconfig

Like your Makefile, this Kconfig file is also not complete. It is included by other Kconfig: this kconfig [6] includes ... which includes ... etc ... which includes your example.

According to the documentation, this piece of kconfig defines a help text:

  • help text: "help" or "---help---" This defines a help text. The end of the help text is determined by the indentation level, this means it ends at the first line which has a smaller indentation than the first line of the help text. "---help---" and "help" do not differ in behaviour, "---help---" is used to help visually separate configuration logic from help within the file as an aid to developers.

So, "M" is an option of the program and is not a feature of kconfig. It has nothing to do with Kconfig.

Documentation

You will find kconfig documentation here [7] and makefile documentation here [8].

URLs

[1] https://github.com/torvalds/linux/blob/master/Makefile

[2] https://github.com/torvalds/linux/blob/master/drivers/Makefile

[3] https://github.com/torvalds/linux/blob/master/drivers/media/Makefile

[4] https://github.com/torvalds/linux/blob/master/drivers/media/usb/Makefile

[5] https://github.com/torvalds/linux/blob/master/drivers/media/usb/Makefile

[6] https://github.com/torvalds/linux/blob/master/Kconfig

[7] https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt

[8] https://www.kernel.org/doc/Documentation/kbuild/makefiles.txt

Upvotes: 4

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