[Buildroot] building fbtft framebuffer drivers into buildroot.

[Yann E. MORIN <yann.morin.1998@free.fr>]

On 2014-12-26 15:04 +0100, Thomas Petazzoni spake thusly:
> Dear Yann E. MORIN,
> 
> On Fri, 26 Dec 2014 11:20:29 +0100, Yann E. MORIN wrote:
> 
> > I've had a look at this package, and unfortunately, it will be hard to
> > get it packaged in Buildroot.
> > 
> > The problem is that this kernel module does not compile as an
> > out-of-tree module, and their buildsystem is made so that it requires
> > the kernel be patched.
> > 
> > This is not posible with Buildroot.
> 
> Well, yes and no. Indeed it is much easier to package if the stuff can
> be built as an out-of-tree module. However, we have two examples of
> things packaged in Buildroot that require patching the kernel: Xenomai
> and RTAI. They use a loosely defined model that we could name "Linux
> extension", see linux/linux-ext-*.mk. They basically hook up into the
> Linux build process by adding some stuff to LINUX_PRE_PATCH_HOOKS.
> 
> I recently had a look at the aufs stuff, and it has the same problem:
> not only it is made of modules that can be built out-of-tree, but it
> also needs to patch the kernel (some core VFS changes).
> 
> So, I haven't looked at all the fbtft stuff. If it's a set of
> standalone drivers that don't require any modification to the core of
> the kernel, then indeed, turning them into out-of-tree modules can be a
> good idea. If not, then using the "linux-ext" model can be a solution.

Yes, I know about those linux "extensions".

But the fact is that fbtft is only an additional modules with no impact
on the core of the kernel; it requires "patching" the kernel just
because it wants to add a Kconfig option and a Kbuild sub-directory.

So, it would better be built as an out-of-tree module, rather than be
handled as a kernel extension. Hence the reason I said it would not play
well "as-is" with Buildroot.

Regards,
Yann E. MORIN.

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