Linux DRM: how to tell which (ported) version is in use?

… probed on 2021-11-13 <> showed graphics/drm-current-kmod 5.4.144.g20211012 (i.e. 5.4) from the FreeBSD repository however the DRM might have been superior (master). Re: <> I can't tell whether it would have been 5.5, 5.6 or 5.7. …

Without looking at the port/package name or version:
  • how can I tell the version that's in use by the currently running OS?
(5.4, 5.5, 5.6 or 5.7.)

I can't see anything suitably distinctive in /var/log/messages or /var/log/Xorg.0.log.

With graphics/drm_info I can get, for example:

% drm_info | head -n 2
Node: /dev/dri/card0
├───Driver: radeon (ATI Radeon) version 2.50.0 (20080528)

– however that's not enough to tell the ported version of DRM, and there's no "5." string in full output from drm_info.

Similarly, with graphics/mesa-demos:

% glxgears -info | head -n 5
Running synchronized to the vertical refresh.  The framerate should be
approximately the same as the monitor refresh rate.
GL_RENDERER   = AMD TURKS (DRM 2.50.0 / 14.0-CURRENT, LLVM 12.0.1)
GL_VERSION    = 3.1 Mesa 21.1.8
GL_VENDOR     = X.Org

– not enough to tell the ported version.
I have a line in /var/log/messages
Tuesday:14:39:54.349 mail kernel user notice <6>[drm] Initialized radeon 2.50.0 20080528 for drmn0 on minor 0
No idea what it means