[Buildroot] Build failure with Vivante and QT5 w/ eglfs

["Jérôme Pouiller" <jezz@sysmic.org>]

Hello Gary,

On Friday 04 March 2016 12:02:31 Gary Bisson wrote:
> Antoine, All,
> 
> Adding J?r?me in cc since he's the one behind the x11/fb selection as
> well as qt5 graphics support for i.MX.
> 
> On Fri, Mar 4, 2016 at 10:55 AM, Antoine Tenart
> 
> <antoine.tenart@free-electrons.com> wrote:
> > Hi all,
> > 
> > I've run into a build failure while compiling an image, when
> > building
> > QT5. I made some build tests to narrow down the issue and found the
> > configuration leading to this: when compiling an image with both
> > BR2_PACKAGE_QT5BASE_EGLFS and BR2_PACKAGE_IMX_GPU_VIV_OUTPUT_X11 the
> > build fails with the following error:
> > 
> > http://code.bulix.org/qxj1bn-92391?raw
> 
> Indeed that's a problem. It looks like the question has been raised in
> the Yocto community not so long ago:
> https://github.com/Freescale/meta-fsl-arm/commit/da8f520a
> 
> It looks like their patch is to define EGL_API_FB although X11 is in
> use. I imagine we could do the same using J?r?me's approach but
> depending on EGLFS define:
> https://git.buildroot.net/buildroot/tree/package/freescale-imx/imx-gpu
> -viv/imx-gpu-viv.mk#n55
> 
> However I guess that would only fix the build but would cause issues
> at runtime which might be confusing for users.
> 
> > I understand this configuration can't work, but as this leads to a
> > build issue we might need to think about a solution. We could
> > disallow such a configuration tuple, or fix the build.
> > 
> > Any idea?
> 
> I'm afraid forcing the imx-gpu-viv package output format depending on
> qt5 graphical back end would bring many "recursive dependency" issues.
> 
> J?r?me, what are your thoughts?

An alternative solution would be to rename  EGL_API_FB into 
MESA_EGL_NO_X11_HEADERS. Indeed, since this variable is used by Mesa 
headers, it is the de facto standard way to disable X11 headers 
inclusion.
As far as I remember, Qt5 correctly set MESA_EGL_NO_X11_HEADERS when it 
compile EGLFS.

IMHO, it is the most elegant way to solve compilation problem. It would 
allow to compile Qt5 with both X11 and EGLFS enabled (sure, only one 
backend will work at runtime). However, I afraid to do such deep change 
in Vivante headers.


BR,

-- 
J?r?me Pouiller, Sysmic
Embedded Linux specialist
http://www.sysmic.fr