Re: [Buildroot] [PATCH v2 5/8] package/libcamera-apps: Only enable EGL if both epoxy and xlib_libX11 are selected

From: Thomas Petazzoni via buildroot <buildroot@buildroot.org>
To: John Ernberg <j@j-ernberg.se>
Cc: buildroot@buildroot.org, John Ernberg <john.ernberg@actia.se>,
	 Marcus Folkesson <marcus.folkesson@gmail.com>
Subject: Re: [Buildroot] [PATCH v2 5/8] package/libcamera-apps: Only enable EGL if both epoxy and xlib_libX11 are selected
Date: Wed, 21 Oct 2026 23:48:26 +0200	[thread overview]
Message-ID: <atkwl965cKxez-Es@windsurf> (raw)
In-Reply-To: <20260614155328.304282-6-j@j-ernberg.se>

On Sun, Jun 14, 2026 at 05:53:25PM +0200, John Ernberg wrote:
> Since release 0.2 of the rpicam-apps these dependencies have been required
> if enable_egl=True is given to meson. [1]
> 
> The dependency check was broken since commit 3fac163b9315
> ("package/libcamera-apps: bump to version 1.1.0") in early 2023.
> 
> Link: https://github.com/raspberrypi/rpicam-apps/commit/c8351a09174f143424884081a69b6dd8018f4ba3#diff-a2468a39040f9f883e5b03e1523dd4e73fd43ad9ea87f600772477b890cdd655L18-R22

This commit is only reorganizing meson options, I think the commit
actually introducing the requirement for epoxy+xlib is older than this
one.

> Cc: Marcus Folkesson <marcus.folkesson@gmail.com>
> Signed-off-by: John Ernberg <j@j-ernberg.se>

I believe this would fix:

  https://autobuild.buildroot.net/results/21d/21dcd20d70c12758083733b0e5bc8f1efc671370/build-end.log

> -ifeq ($(BR2_PACKAGE_XORG7),y)
> -LIBCAMERA_APPS_DEPENDENCIES += \
> -	$(if $(BR2_PACKAGE_LIBEPOXY),libepoxy) \
> -	$(if $(BR2_PACKAGE_XLIB_LIBX11),xlib_libX11)
> +ifeq ($(BR2_PACKAGE_LIBEPOXY)$(BR2_PACKAGE_XLIB_LIBX11),yy)
> +LIBCAMERA_APPS_DEPENDENCIES += libepoxy xlib_libX11
>  LIBCAMERA_APPS_CONF_OPTS += -Denable_egl=enabled
>  else
>  LIBCAMERA_APPS_CONF_OPTS += -Denable_egl=disabled

However, I'm not 100% convinced this is the right fix because the
Config.in also has:

	select BR2_PACKAGE_XLIB_LIBX11 if BR2_PACKAGE_XORG7 && (BR2_PACKAGE_HAS_LIBEGL || BR2_PACKAGE_HAS_LIBGL)
	select BR2_PACKAGE_LIBDRM if BR2_PACKAGE_XORG7 && (BR2_PACKAGE_HAS_LIBEGL || BR2_PACKAGE_HAS_LIBGL)
	select BR2_PACKAGE_LIBEPOXY if BR2_PACKAGE_XORG7 && (BR2_PACKAGE_HAS_LIBEGL || BR2_PACKAGE_HAS_LIBGL)

I can't really wrap my head around what's the right way to deal with
all those dependencies.

With your change:

 +ifeq ($(BR2_PACKAGE_LIBEPOXY)$(BR2_PACKAGE_XLIB_LIBX11),yy)
 +LIBCAMERA_APPS_DEPENDENCIES += libepoxy xlib_libX11
  LIBCAMERA_APPS_CONF_OPTS += -Denable_egl=enabled

We may be passing -Denable_egl=enabled even if there's no OpenGL
support at all: libepoxy can now be enabled without any OpenGL
provider enabled, and xlib_libx11 also doesn't guarantee that we have
OpenGL support.

I honestly don't quite understand those selects in the Config.in
file. My understanding is that libcamera-apps has a preview/ folder
with several variants: drm-preview, egl-preview, wayland-egl-preview,
qt-preview and null-preview. Maybe we should instead handle these more
clearly/explicitly?

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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