Re: [Buildroot] [RFC PATCH] package: {libgl, libglvnd, mesa3d}: Propagate libglvnd GL provider to libgl dependencies

From: Thomas Petazzoni via buildroot <buildroot@buildroot.org>
To: John Ernberg <j@j-ernberg.se>
Cc: buildroot@buildroot.org, Adam Ford <aford173@gmail.com>,
	 Bernd Kuhls <bernd@kuhls.net>,
	Joseph Kogut <joseph.kogut@gmail.com>,
	 Romain Naour <romain.naour@gmail.com>,
	"Yann E. MORIN" <yann.morin.1998@free.fr>
Subject: Re: [Buildroot] [RFC PATCH] package: {libgl, libglvnd, mesa3d}: Propagate libglvnd GL provider to libgl dependencies
Date: Sun, 18 Oct 2026 22:41:34 +0200	[thread overview]
Message-ID: <atUtmzafWnVtVm-t@windsurf> (raw)
In-Reply-To: <20261018160651.349981-1-j@j-ernberg.se>

Hello John,

[+Yann since he added libglvnd initially.]

On Sun, Oct 18, 2026 at 06:06:51PM +0200, John Ernberg wrote:

> xwayland will fail with a similar error, not finding dri.
> 
> This is because dri.pc is in this configuration is provided by mesa3d,
> but libgl is provided by libglvnd, which does not depend on mesa3d
> (because mesa3d depends on libglvnd to build the interface used by
> libglvnd).
> 
> If libglvnd is extended to cover the nvidia-driver, dri.pc would be
> provided by mesa3d-headers.
> 
> It seems that only libgl usually needs this extra bit, so EGL and GLES
> are left untouched.

Thanks for this new iteration. It is really annoying that mesa3d needs
libglvnd, as it prevents from doing the natural thing:

	libgl -> libglvnd -> real OpenGL provider -> mesa3d

In the end this indeed means that the only option is to do something
like this:

	libgl -> libglvnd
	      -> real OpenGL provider

Now, the questions that come up are:

- Why do you need libglvnd in the first place? Why don't you just
  enable mesa3d?

- Why do we have libglvnd at all? It has been added in 2020, but so
  far only mesa3d has been made "suitable" to be used behind libglvnd,
  and since we have only one OpenGL provider able to be used behind
  libglvnd, the abstraction that libglvnd provides seems quite
  useless, no?

So shouldn't we drop libglvnd entirely?

Otherwise, I guess we would indeed need some additional virtual
package like "real-libgl". mesa3d would provide libgl when !libglvnd,
and would provide real-libgl when libglvnd. And libgl would add a
dependency on real-libgl when libglvnd is enabled. This is a bit like
your proposal John, just generalized a bit so that potentially other
OpenGL providers than mesa3d can be used behind libglvnd. But before
going this route, let's figure out if we want to keep libglvnd at all.

Thanks!

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