[systemd-devel] udev database backwards compatibility guarantees

[Lennart Poettering]

On Thu, 11.09.14 10:49, Alexander Larsson (alexl at redhat.com) wrote:

> Hi, I'm looking at creating a runtime/app thing for Gnome in the style
> of:
> http://0pointer.net/blog/revisiting-how-we-put-together-linux-systems.html
> 
> However, I noticed that some core dependencies like mesa uses libudev.
> And in fact, needs user-set additional info not in sysfs. In particular,
> it reads ID_PATH_TAG on render device nodes to pick what GPU to use in
> multi-gpu situations (PRIME):
> http://lists.freedesktop.org/archives/mesa-dev/2014-June/061798.html
> 
> It seems to me that this means I need the host /run/udev inside the
> application. I know that the udev database format changed in the past,
> but can I rely on it being stable in the future, even if the host udev
> is rev:ed to a later version than what is in the application runtime?
> 
> Of course, there is also the question of /dev and /sys management in
> sandboxed apps in general. Clearly any "modern" app will require some
> real devices for things like direct rendering. But it would be ideal to
> not expose "everything". How do we see this working?

Good question. Ideally we wouldn't expose any raw devices to apps, but
I figure this is not going to suffice (already with video4linux and
things).

Kay, any ideas on the udev database stability?

Lennart

-- 
Lennart Poettering, Red Hat