[PATCH weston 1/4] gl_renderer: allow GL Renderer to be disabled with --disable-gl-renderer

[Pekka Paalanen]

On Sat,  5 Sep 2015 15:01:37 +0100
John Sadler <deathofathousandpapercuts at gmail.com> wrote:

> Commit a352580285 introduced a dependency on `libdrm` whenever
> EGL support is enabled. However, when building for Raspberry Pi
> with EGL enabled this is an unwelcome dependency, and we don't
> need the GL Renderer anyway.
> 
> This commit introduces a separate configure option:
>     --disable-gl-renderer
> 
> Which allows building of the GL Renderer to be disabled, and
> the `libdrm` dependency along with it.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91884
> 
> Signed-off-by: John Sadler <deathofathousandpapercuts at gmail.com>
> ---
>  Makefile.am  | 2 +-
>  configure.ac | 9 +++++++++
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile.am b/Makefile.am
> index 62719c9..9968b7f 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -198,7 +198,7 @@ westoninclude_HEADERS =				\
>  	shared/zalloc.h				\
>  	shared/platform.h
>  
> -if ENABLE_EGL
> +if ENABLE_GL_RENDERER
>  module_LTLIBRARIES += gl-renderer.la
>  gl_renderer_la_LDFLAGS = -module -avoid-version
>  gl_renderer_la_LIBADD = $(COMPOSITOR_LIBS) $(EGL_LIBS)
> diff --git a/configure.ac b/configure.ac
> index 17a3754..f832ada 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -80,13 +80,22 @@ if test "x$enable_devdocs" != "xno"; then
>  fi
>  AM_CONDITIONAL(ENABLE_DEVDOCS, test "x$enable_devdocs" = "xyes")
>  
> +AC_ARG_ENABLE(gl-renderer, [  --disable-gl-renderer],,
> +              enable_gl_renderer=yes)
> +
>  AC_ARG_ENABLE(egl, [  --disable-egl],,
>                enable_egl=yes)
> +
>  AM_CONDITIONAL(ENABLE_EGL, test x$enable_egl = xyes)
>  if test x$enable_egl = xyes; then
>  	AC_DEFINE([ENABLE_EGL], [1], [Build Weston with EGL support])
>  	PKG_CHECK_MODULES(EGL, [egl >= 7.10 glesv2])
>          PKG_CHECK_MODULES([EGL_TESTS], [egl >= 7.10 glesv2 wayland-client wayland-egl])
> +fi
> +
> +AM_CONDITIONAL(ENABLE_GL_RENDERER, test x$enable_gl_renderer = xyes -a x$enable_egl = xyes)
> +if test x$enable_gl_renderer = xyes -a x$enable_egl = xyes; then
> +	AC_DEFINE([ENABLE_GL_RENDERER], [1], [Build GL Renderer])
>  	PKG_CHECK_MODULES([GL_RENDERER], [libdrm])
>  fi
>  

Hi John,

it's hard for me to make my mind on this patch. On one hand, sure, why
not, but on the other hand, the option feels a bit awkward.

If one uses this option, then all backends that use gl-renderer by
default will fail to init by default. But, I would not like to
litter #ifdef WESTON_GL_RENDERER around either. Automatic fallback to
Pixman on gl-renderer init failure is also a bit subtle for testing, as
you'd have to check the logs to see which renderer came up.

We already have options to disable every single backend. What if we
disabled gl-renderer automatically when all backends that could
possibly use it are disabled?

Another alternative that comes to mind is to put rpi-backend's EGL
support behind a --enable-rpi-proprietary-egl, so that you could use
that *and* --disable-egl. That switch would be easy to remove along
with the rpi-backend once the time comes.

Maybe the former approach would be better than the latter? Less options
to confuse users.


Thanks,
pq
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