[CMake] linux kernel module, output directory and clean issues

[Alan W. Irwin]

On 2007-08-16 15:18+0100 Tim Schooley wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Hi all!
>
> [My first post, please bear with me...]
>
> I've been porting a Makefile project to use CMake. Thankfully, it's gone
> very smoothly, and now I'm just trying to iron out some ripples. CMake
> truly rocks.
>
> I found some advice on this mailing list for building linux kernel
> modules, and I'm using the following for it:
>
> - ---
>
> Set( DRIVER_FILE mydriver.ko )
> Set( KERNEL_DIR "/lib/modules/${CMAKE_SYSTEM_VERSION}/build" )
> Set( KBUILD_CMD ${CMAKE_MAKE_PROGRAM}
>                -C ${KERNEL_DIR}
>                M=${CMAKE_CURRENT_SOURCE_DIR} modules)
>
> Add_Custom_Command( OUTPUT ${DRIVER_FILE}
>                    COMMAND ${KBUILD_CMD}
>                    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
>                    DEPENDS ${src} Kbuild VERBATIM )
>
> Add_Custom_Target ( driver ALL DEPENDS ${DRIVER_FILE} )
>
> - ---
>
> My issue is this: no matter how I specify the output, I cannot for the
> life of me get the mydriver.ko file to be outputted to the
> ${PROJECT_BINARY_DIR}/bin directory. I've searched around for similar
> issues/code, but come to a dead end.

Hi Tim:

To address the CMake issue of where it expects to find files,
use full pathnames for all files, and drop the
WORKING_DIRECTORY.  That is, do something like the following:

Add_Custom_Command( OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${DRIVER_FILE}
                    COMMAND ${KBUILD_CMD}
                    DEPENDS ${src} Kbuild VERBATIM )

Add_Custom_Target ( driver ALL DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/${DRIVER_FILE} )

Without the WORKING_DIRECTORY the external make command you access with
${CMAKE_MAKE_PROGRAM} should be issued from the ${CMAKE_CURRENT_BINARY_DIR}
directory (which I assume is identical to ${PROJECT_BINARY_DIR}/bin in your
above example.  However, if the above does not work, you can be absolutely
specific by doing, e.g.,

Add_Custom_Command( OUTPUT ${CMAKE_BINARY_DIR}/bin/${DRIVER_FILE}
                    COMMAND ${KBUILD_CMD}
                    WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/bin
                    DEPENDS ${src} Kbuild VERBATIM )

Add_Custom_Target ( driver ALL DEPENDS ${CMAKE_BINARY_DIR}/bin/${DRIVER_FILE} )

Anyhow, one of the two variations above should take care of the CMake
issues.  That leaves the issue of where the external make command outputs
its files. I am guessing here that it will output the ${DRIVER_FILE} result
to ${CMAKE_BINARY_DIR}/bin/ or what I think is the equivalent
${CMAKE_CURRENT_BINARY_DIR}.  If the external make programme does not
cooperate that way by default then you may have to try additional make
options to get it to do that or add a specific stanza to copy the output
file from make to the directory that you want.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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Linux-powered Science
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