[Buildroot] [PATCH v2 2/3] package/waffle: new package

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello Romain,

On Sun, 11 Feb 2018 17:21:35 +0100, Romain Naour wrote:
> Backport an upstream patch fixing a build issue with musl toolchains.
> Add a new patch fixing build with Wayand without X11.
> 
> Signed-off-by: Romain Naour <romain.naour@gmail.com>

I finally took some time to look at this package again, and I think the
dependencies are not correctly handled.

> +config BR2_PACKAGE_WAFFLE
> +	bool "waffle"
> +	depends on BR2_PACKAGE_XORG7 || BR2_PACKAGE_WAYLAND

Due to this dependency, you cannot do a build which has just mesa3d as
a gbm/egl provider + udev, which is a valid configuration supported by
waffle.

I.e, the following defconfig builds waffle properly:

BR2_arm=y
BR2_cortex_a8=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_INIT_NONE=y
BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y
BR2_SYSTEM_BIN_SH_NONE=y
# BR2_PACKAGE_BUSYBOX is not set
BR2_PACKAGE_MESA3D=y
BR2_PACKAGE_MESA3D_DRI_DRIVER_SWRAST=y
BR2_PACKAGE_MESA3D_OPENGL_EGL=y
BR2_PACKAGE_WAFFLE=y
# BR2_TARGET_ROOTFS_TAR is not set

> +	depends on BR2_PACKAGE_HAS_LIBGL || BR2_PACKAGE_HAS_LIBEGL
> +	# OpenGL ES (1,2,3) libraries are loaded at runtime when needed
> +	# in addition to LIBGL or LIBEGL.
> +	depends on BR2_PACKAGE_HAS_LIBGLES

This dependency means that you cannot build waffle at all if there's no
GLES support. Therefore a desktop configuration that provides GL will
not allow building waffle. That's not good.

Looking more closely into the Waffle build system, it has four
"backends", each having their own dependencies. At least one "backend"
must be enabled, otherwise Waffle will refuse to build. The "backends"
are:

 - glx, which needs full OpenGL + x11-xcb
 - wayland, which needs wayland-client, wayland-egl and EGL
 - x11-egl, which needs x11-xcb and EGL
 - gbm, which needs gbm, libudev and EGL

So the easiest is perhaps to map this to hidden Config.in options,
maybe something like:

config BR2_PACKAGE_WAFFLE_SUPPORTS_GLX
	bool
	default y if BR2_PACKAGE_HAS_LIBGL && BR2_PACKAGE_XORG7

config BR2_PACKAGE_WAFFLE_SUPPORTS_WAYLAND
	bool
	default y if BR2_PACKAGE_WAYLAND && BR2_PACKAGE_HAS_LIBEGL_WAYLAND

config BR2_PACKAGE_WAFFLE_SUPPORTS_X11_EGL
	bool
	default y if BR2_PACKAGE_HAS_LIBEGL && BR2_PACKAGE_XORG7

config BR2_PACKAGE_WAFFLE_SUPPORTS_GBM
	bool
	# mesa3d is for now the only GBM provider, and it is enabled
	# together with its EGL support
	default y if BR2_PACKAGE_HAS_LIBEGL && BR2_PACKAGE_MESA3D_OPENGL_EGL && BR2_PACKAGE_HAS_UDEV

config BR2_PACKAGE_WAFFLE
	bool "waffle"
	depends on BR2_PACKAGE_WAFFLE_SUPPORTS_GLX || \
		BR2_PACKAGE_WAFFLE_SUPPORTS_WAYLAND || \
		BR2_PACKAGE_WAFFLE_SUPPORTS_X11_EGL || \
		BR2_PACKAGE_WAFFLE_SUPPORTS_GBM
	select BR2_PACKAGE_XLIB_LIBX11 if BR2_PACKAGE_WAFFLE_SUPPORTS_GLX || BR2_PACKAGE_WAFFLE_SUPPORTS_X11_EGL
	select BR2_PACKAGE_LIBXCB if BR2_PACKAGE_WAFFLE_SUPPORTS_GLX || BR2_PACKAGE_WAFFLE_SUPPORTS_X11_EGL

I don't think we need a Config.in comment to document those
dependencies. They are anyway waaaay too complicated to be summarized
in a Config.in comment.

> diff --git a/package/waffle/waffle.hash b/package/waffle/waffle.hash
> new file mode 100644
> index 0000000000..5dfb976f2f
> --- /dev/null
> +++ b/package/waffle/waffle.hash
> @@ -0,0 +1,3 @@
> +# Locally calculated
> +sha256 d662f6743f688dc5ea4b7d29f558eb54bd8f57350080f04a006693d22e5d1d5b  waffle-v1.5.2.tar.gz
> +sha256 630844d1911c8a1b7b888a1de9097c4860b7e381362fd5aa64141d58ab7ecc9b  LICENSE.txt
> diff --git a/package/waffle/waffle.mk b/package/waffle/waffle.mk
> new file mode 100644
> index 0000000000..741bc8e349
> --- /dev/null
> +++ b/package/waffle/waffle.mk
> @@ -0,0 +1,48 @@
> +################################################################################
> +#
> +# waffle
> +#
> +################################################################################
> +
> +WAFFLE_VERSION = v1.5.2
> +WAFFLE_SITE = $(call github,waffle-gl,waffle,$(WAFFLE_VERSION))
> +WAFFLE_INSTALL_STAGING = YES
> +WAFFLE_LICENSE = BSD-2-Clause
> +WAFFLE_LICENSE_FILES = LICENSE.txt
> +
> +WAFFLE_DEPENDENCIES = host-pkgconf
> +
> +WAFFLE_CONF_OPTS = -Dwaffle_build_tests=OFF \
> +	-Dwaffle_build_examples=OFF \
> +	-Dwaffle_build_manpages=OFF \
> +	-Dwaffle_build_htmldocs=OFF
> +
> +ifeq ($(BR2_PACKAGE_WAYLAND)$(BR2_PACKAGE_HAS_LIBEGL_WAYLAND),yy)

You can replace this condition with BR2_PACKAGE_WAFFLE_SUPPORTS_WAYLAND.

> +WAFFLE_DEPENDENCIES += libegl wayland
> +WAFFLE_CONF_OPTS += -Dwaffle_has_wayland=ON
> +else
> +WAFFLE_CONF_OPTS += -Dwaffle_has_wayland=OFF
> +endif
> +
> +ifeq ($(BR2_PACKAGE_XLIB_LIBX11)$(BR2_PACKAGE_LIBXCB)$(BR2_PACKAGE_HAS_LIBEGL),yyy)

This one by BR2_PACKAGE_WAFFLE_SUPPORTS_X11_EGL

> +WAFFLE_DEPENDENCIES += libegl libxcb xlib_libX11
> +WAFFLE_CONF_OPTS += -Dwaffle_has_x11_egl=ON
> +else
> +WAFFLE_CONF_OPTS += -Dwaffle_has_x11_egl=OFF
> +endif
> +
> +ifeq ($(BR2_PACKAGE_XLIB_LIBX11)$(BR2_PACKAGE_LIBXCB)$(BR2_PACKAGE_HAS_LIBGL),yyy)

This one by BR2_PACKAGE_WAFFLE_SUPPORTS_GLX

> +WAFFLE_DEPENDENCIES += libgl libxcb xlib_libX11
> +WAFFLE_CONF_OPTS += -Dwaffle_has_glx=ON
> +else
> +WAFFLE_CONF_OPTS += -Dwaffle_has_glx=OFF
> +endif
> +
> +ifeq ($(BR2_PACKAGE_MESA3D_OPENGL_EGL)$(BR2_PACKAGE_HAS_UDEV),yy)

And this one by BR2_PACKAGE_WAFFLE_SUPPORTS_GBM

> +WAFFLE_DEPENDENCIES += libegl mesa3d udev

I would say adding mesa3d here in the dependencies is a bit useless,
because libegl is provided by mesa3d anyway when
BR2_PACKAGE_MESA3D_OPENGL_EGL.

You had a "depends on BR2_PACKAGE_HAS_LIBGLES" because waffle can use
OpenGLES. But it seems like a runtime dependency, not a build time
dependency. Could you check this ?

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com