Need udev_hwdb for wlroots >= 0.16

[jbeich]

In wlroots#3541 the hardcoded list of EDID manufacturers was replaced by udev_hwdb_new which is not implemented on FreeBSD:

libudev-devd/udev-hwdb.c

Lines 33 to 39 in a91c357

	LIBUDEV_EXPORT struct udev_hwdb *
	udev_hwdb_new(struct udev *udev)
	{
	TRC("(%p", udev);
	UNIMPL();
	return (NULL);
	}

$ pkg install sway-devel
$ vidcontrol -s 1 </dev/ttyv0 # aka Ctrl+Alt+F1
$ if [ -z "$XDG_RUNTIME_DIR" ]; then export XDG_RUNTIME_DIR=/tmp; fi
$ seatd-launch sway
[...]
00:00:00.003 [ERROR] [wlr] [backend/drm/backend.c:187] udev_hwdb_new failed
[...]

CC @emersion @unrelentingtech

[emersion]

Oh. Since the CI build succeeded I just assumed it would be fine for FreeBSD.

Would something like this help? https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3446

[wulf7]

struct udev_hwdb is stubbed in master branch now. Please test.

hwdb itself is not implemented yet though.

[jbeich]

Would something like this help? https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3446

Sure. libudev-zero also doesn't implement hwdb. Obviously, the path to pnp.ids may need to be configurable (or derived from datadir) as hwdata doesn't have a .pc (pkg-config) file.

I was thinking there maybe more consumers but hard to finding anything portable to FreeBSD, not a FFI/interpose wrapper and doesn't already support pnp.ids. For example, emulators/nemu, graphics/colord (has pnp.ids fallback), x11/gnome-desktop can use udev_hwdb but the code is disabled on FreeBSD either in the port or the source.

struct udev_hwdb is stubbed in master branch now. Please test.

Doesn't help much: wlroots no longer shows the error but EDID manufacturer remains unexpanded (e.g., GSM instead of Goldstar Company Ltd). Affects wlr-output-management-unstable-v1 consumers like wdisplays (description), wlr-randr (description), kanshi (pattern matching), etc.

[illiliti]

Please do not implement udev_hwdb API. We should look into cross-platform approach instead of playing defensive by adding linux-specific and generally harmful APIs.

[wulf7]

udev_hwdb looks like simple udev-oriented key-value database. The only linux-specific part is udev, not the code itself at least in eudev version: https://github.com/eudev-project/eudev/blob/master/src/libudev/libudev-hwdb.c

Are there any alternative solution?

[illiliti]

Are there any alternative solution?

https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3638

[wulf7]

IMO best I can do is to extract hwdb-related code from udev/eudev in to separate udev-free library libhwdb which can be used as drop-in replacement of udev-hwdb

[illiliti]

I asked emersion yesterday about this idea and he said since format of hwdata is simple, the need for libhwdb is unnecessary.

[wulf7]

I created whdb branch https://github.com/wulf7/libudev-devd/tree/hwdb which includes hwdb.bin parser imported from eudev.
The imported code is GPL-ed thus disabled by default. To enable it -Denable-gpl=true -Dwith-hwdb=/path/to/hwdb.bin options should be passed to meson at configure stage.

The code is only compile tested now. I have no intention to rewrite it to make it permissive licensed yet.