Re: how to use 'KBUILD_SRC' in Linux kernel Makefile

[Sam Ravnborg]

On Tue, Dec 22, 2009 at 04:39:51PM +0800, kai yang wrote:
> I want to compily the Linux kernel 2.6 kernel in an alternate place
> and do not use the Makefile in top directory of kernel. (not different
> output directory)
> So I want to modify a makefile from Linux kernel 2.6 Makefile, but it
> seens not so easy to me, becaust many rules in Makefile(in top level
> directory or oher directory like /arch/arm/Makefile) use the PATH only
> available in CURRENT DIRECTORY. I want to modify only one Makefile and
> don't affect others.
> 
> I notice that there is a tag in kernel Makefile: KBUILD_SRC, is that
> useful for me? But I didn't get how to use this tag and the Makefile
> only says:
> 
>     # KBUILD_SRC is set on invocation of make in OBJ directory
>     # KBUILD_SRC is not intended to be used by the regular user (for now)

If you try "make help" then kbuild (the linux kernel build system)
will tell you that you can use:

    make O=some/dir

Note: You need to be in the source directory of the kernel when
you do this, as 'help' is just another target in the kernel Makefile.

As simple as that - and no changes in the Makefile are required.
For further questions on this topic please use the kbuild
mailing list:

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This list is for gmake things - not the the random programs using gmake.

        Sam