:: Re: [DNG] vdev
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Szerző: Didier Kryn
Dátum:  
Címzett: dng
Tárgy: Re: [DNG] vdev
Le 05/08/2016 19:30, richard lucassen a écrit :
> On Fri, 5 Aug 2016 18:55:04 +0200
> Didier Kryn <kryn@???> wrote:
>
>>> Anyone here running vdev? I just looked around a bit, but there
>>> seems to be little activity:
>>>
>>> https://git.devuan.org/unsystemd/vdev/activity
>>       No news from Jude for almost one year :-(
> When I posted this topic I expected to have at least a bunch of
> replies. Yesterday I updated a freshly installed Devuan Jessie and I got
> a warning about the network devices that are going to be changed and
> that the 70-persistent-network.rules was going to be ignored. IOW: I
> think vdev is very important for a systemd-free distro like Devuan.

>
> Today I gave it a try on an ascii machine, but the README.md that comes
> with a "git clone" seems to be outdated. And when following the
> instructions on
>
> https://git.devuan.org/unsystemd/vdev
>
> I ran into a dependency hell. Unfortunately I'm not a skilled
> programmer otherwise I would certainly have spent some time to
> contribute.
>
> There is quite some activity here, but when I post a topic about a
> quite important unsystemd daemon there is almost no reply. That's
> rather alarming IMHO....
>
>>       I'm partial time reading documentation and sources and
>> considering rolling my own hotplugger, simpler than vdev - Jude has
>> done an enormous work and vdev is a complex software with hundreds of
>> scripts, too complex for me.
> [..]

>
> I have no idea if there are alternatives to udev. If you're writing
> your own hotplugger, wouldn't it be an idea to statically create all
> possible devices in /dev (MAKEDEV) and to have the hotplugger just add
> and remove symlinks? I know, I'm a noob, I have no idea what I'm talking
> about but you never know :)
>
> R.
>


     Creating block and char devices after the drivers have been 
initialized is relatively easy because all devices are available in 
/sys/block/dev and /sys/char/dev and only need to copied to /dev - you 
only want to customize owner/permission. AFAIU, appart adjusting 
owner/permission, this is done by the kernel if it is compiled with the 
devtmpfs feature enabled.


     But there is a problem when the driver is in a loadable module or 
when a firmware is needed. Module and firmware loading are done by a 
userspace application, and is part of the initialization of the driver, 
and the device file is created by the driver when it is ready; only 
after that can you copy it to /dev.


     Also I think care must be taken to not have a race condition 
between the hotplugging and the devices aready present.


     We all miss Jude and a decisive contribution from his part to have 
a running Vdev on Devuan. It's more than 2 years since the inception of 
Vdev and more than one year since Jude has "almost finished" it. Yet we 
haven't a replacement for Udev, while it is more and more integrated to 
systemd. I see this as a major threat. I'm deceived that Skarnet hasn't 
written their own, because it's more critical than a supervisor.


     Didier