Re: [RFC] dma-buf: Implement test module

[Thierry Reding]

On Tue, Mar 25, 2014 at 07:01:10PM +0100, Sam Ravnborg wrote:
> > 
> > There are two things that don't work too well with this. First this
> > causes the build to break if the build machine doesn't have the new
> > public header (include/uapi/linux/dma-buf.h) installed yet. So the only
> > way to make this work would be by building the kernel once with SAMPLES
> > disabled, install the headers and then build again with SAMPLES enabled.
> > Which really isn't very nice.
> > 
> > One other option that I've tried is to modify the include path so that
> > the test program would get the in-tree copy of the public header file,
> > but that didn't build properly either because the header files aren't
> > properly sanitized and therefore the compiler complains about it
> > (include/uapi/linux/types.h).
> > 
> > One other disadvantage of carrying the sample program in the tree is
> > that there's only infrastructure to build programs natively on the build
> > machine. That's somewhat unfortunate because if you want to run the test
> > program on a different architecture you have to either compile the
> > kernel natively on that architecture (which isn't very practical on many
> > embedded devices) or cross-compile manually.
> > 
> > I think a much nicer solution would be to add infrastructure to cross-
> > compile these test programs, so that they end up being built for the
> > same architecture as the kernel image (i.e. using CROSS_COMPILE).
> > 
> > Adding Michal and the linux-kbuild mailing list, perhaps this has been
> > discussed before, or maybe somebody has a better idea on how to solve
> > this.
> I actually looked into this some time ago.
> May try to dust off the patch.
> IIRC the kernel provided headers were used for building - not the one installed on the machine.
> And crosscompile were supported.

That sounds exactly like what I'd want for this. If you need any help,
please let me know.

Thanks,
Thierry

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