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

[Giulio Camuffo]

2015-09-10 12:13 GMT+03:00 Pekka Paalanen <ppaalanen at gmail.com>:
> 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.
>

I would rather see the libdrm dependency being turned into a soft
dependency, so that the dmabuf stuff would be disabled if libdrm is
not present. Not all the EGL stacks are based on libdrm and i see no
reason to require that for basic EGL functionality.


--
Giulio

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