meson: Add options to control optional parts

Distributions want explicit control over optional parts so they can
state runtime dependencies before building. Let's restore the
functionality autotools used to provide.

Where possible, the selection is done by choosing whether to build a
particular item and the option name is build_$item. Example:
build_overlay. Where not possible, the option name is
with_$item. Example: with_valgrind.

Array options require a bump of required meson version to 0.44. Debian
stable has meson 0.37 which is already too old, stable-backports has
0.45, CI uses 0.45. Mesa's meson requirement is 0.44.1, for a
perspective.

Note, the old hack for not building docs when cross-compiling is
gone, as doc building can be explicitly controlled now.

v2: glib not optional
v3: bump meson version to 0.44

Signed-off-by: Petri Latvala <petri.latvala@intel.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Eric Anholt <eric@anholt.net>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 36 insertions, 10 deletions

diff --git a/overlay/meson.build b/overlay/meson.build
index 546c8377..46d2d494 100644
--- a/overlay/meson.build
+++ b/overlay/meson.build
@@ -14,20 +14,35 @@ gpu_overlay_src = [
 	'rc6.c',
 ]
 
-xv = dependency('xv', required : false)
-x11 = dependency('x11', required : false)
-xext = dependency('xext', required : false)
-dri2proto = dependency('dri2proto', version : '>= 2.6', required : false)
-cairo_xlib = dependency('cairo-xlib', required : false)
-xrandr = dependency('xrandr', version : '>=1.3', required : false)
+xv_backend_required = false
+xlib_backend_required = false
+build_xv_backend = overlay_backends.contains('xv') or overlay_backends.contains('auto')
+build_xlib_backend = overlay_backends.contains('x') or overlay_backends.contains('auto')
+if _overlay_required
+	xv_backend_required = overlay_backends.contains('xv')
+	xlib_backend_required = overlay_backends.contains('x')
+endif
+
+xv = dependency('xv', required : xv_backend_required)
+x11 = dependency('x11', required : xv_backend_required)
+xext = dependency('xext', required : xv_backend_required)
+dri2proto = dependency('dri2proto',
+		       version : '>= 2.6',
+		       required : xv_backend_required or xlib_backend_required)
+cairo_xlib = dependency('cairo-xlib', required : xlib_backend_required)
+xrandr = dependency('xrandr', version : '>=1.3', required : _overlay_required)
 
 gpu_overlay_deps = [ realtime, math, cairo, pciaccess, libdrm,
 	libdrm_intel, lib_igt_perf ]
 
 both_x11_src = ''
 
+with_xv_backend = false
+with_xlib_backend = false
+backends_strings = []
+
 gpu_overlay_cflags = []
-if xv.found() and x11.found() and xext.found() and dri2proto.found()
+if build_xv_backend and xv.found() and x11.found() and xext.found() and dri2proto.found()
 	both_x11_src = 'x11/position.c'
 	gpu_overlay_src += [
 		'x11/dri2.c',
@@ -38,20 +53,24 @@ if xv.found() and x11.found() and xext.found() and dri2proto.found()
 	]
 	gpu_overlay_deps += [ xv, x11, xext, dri2proto ]
 	gpu_overlay_cflags += [ '-DHAVE_OVERLAY_XVLIB' ]
+	with_xv_backend = true
+	backends_strings += 'Xv'
 endif
 
-if cairo_xlib.found() and xrandr.found() and dri2proto.found()
+if build_xlib_backend and cairo_xlib.found() and dri2proto.found()
 	both_x11_src = 'x11/position.c'
 	gpu_overlay_src += 'x11/x11-window.c'
 	gpu_overlay_deps += [ cairo_xlib, dri2proto ]
 	gpu_overlay_cflags += [ '-DHAVE_OVERLAY_XLIB' ]
+	with_xlib_backend = true
+	backends_strings += 'X'
 endif
 
 gpu_overlay_src += both_x11_src
 
 gpu_overlay_src += 'kms/kms-overlay.c'
 
-leg = find_program('leg', required : false)
+leg = find_program('leg', required : _overlay_required)
 if leg.found()
 	leg_file = custom_target('tracepoint_format',
 		output: 'tracepoint_format.h',
@@ -62,10 +81,17 @@ else
 	message('WARNING: leg command not found, disabling overlay; try : apt-get install peg')
 endif
 
-if leg.found() and xrandr.found() and cairo.found()
+if _build_overlay and ['x86', 'x86_64'].contains(host_machine.cpu_family()) and libdrm_intel.found() and leg.found() and xrandr.found() and cairo.found() and (with_xlib_backend or with_xv_backend)
 	executable('intel-gpu-overlay', gpu_overlay_src,
 			include_directories : inc,
 			c_args : gpu_overlay_cflags,
 			dependencies : gpu_overlay_deps,
 			install : true)
+	build_info += 'Build overlay: Yes'
+	build_info += 'Overlay backends: ' + ','.join(backends_strings)
+else
+	if _overlay_required
+		error('Cannot build overlay due to missing dependencies')
+	endif
+	build_info += 'Build overlay: No'
 endif