On Tue, Jul 07, 2015 at 07:40:51PM +0200, shraptor wrote:
> On 2015-07-07 17:45, Jude Nelson wrote:
> >Hey everyone,
> >
> >I have the latest news for vdev:
> >
> >* [EXPERIMENTAL] Vdevd now has actions and helpers that will cause it
> >to generate and propagate device events to libudev-compat clients. 
> >Libudev-compat clients should receive hotplug events as they would
> >have with libudev, and they should be able to enumerate devices. 
> >This means that it should be possible now to run X11 with vdevd and
> >libudev-compat, without needing an xorg.conf.  To do so, you'll need
> >to symlink vdev's /dev/metadata/udev to /run/udev.
>
> CONFIRMED WORKING - a great milestone Jude, F***ing good work!
>
> Both keyboard and mouse working without Xorg.conf :-)
>
> When inserting flash memory sticks they get autodetected and device
> nodes created :-)

I presume that this is not over devtmpfs, so you know it's vdev.

> Question This is working without a value for
> /proc/sys/kernel/hotplug so it is not used and
> only for udev???

Linux handles hotplug events in multiple ways:

- /proc/sys/kernel/hotplug (aka "hotplug helper"):
On each hotplug event, the kernel starts the hotplug helper with
an appropriate environment.
hotplug, hotplug2, and mdev/smdev use this.

- netlink:
A daemon connects to the kernel and listens for hotplug events.
udev, s6-devd, nldev, and vdev use this.

- devtmpfs:
The kernel maintains a filesystem in RAM containing all devices that
are present, and at hotplug the kernel automatically adds a new device
with default permissions and name.
This can sometimes be used alone; udev and perhaps Android's hotplug
solution rely on this and change the permissions/owners/... after the
fact.

Hopefully that clarifies things for you.


Thanks,
Isaac Dunham