[Lxc-users] Dynamic devices...

Michael H. Warfield mhw at WittsEnd.com
Sun Mar 7 16:19:30 UTC 2010

On Sun, 2010-03-07 at 15:48 +0100, Daniel Lezcano wrote:

: - Big snip...

> At this point, the udev events for the network devices should be 
> implemented to send events only for the container where the network 
> devices belong.
> And then generalize the udev events for all the containers.

> When udev per container will be implemented, I will be curious to see a 
> "good" lxc.cgroup.devices configuration :)

But you've got a huge problem there anyways that I've recognized right
from the very get go.  Those are based on major and minor numbers and
the whole precept of udev (and devfs before it) is that those should no
longer be needed to be fixed.  There are several drivers that are both
in the primary kernel source tree, such as my own "ip2" multiport serial
interface, and outside of the tree, such as x10dev, that use HUGE
numbers of devices that really just do not NEED a fixed major number.
The Intelliport II driver (ip2) has three entire major numbers assigned
to it from the dark ancient days of the 1.x kernel!  In a fixed
allocation scheme, it needed them!  It supports up to 256 high speed
serial ports (all the minors that were available in a major) and needed
both raw and cooked interfaces (there go two majors) and a couple of per
driver and per board control interfaces (and there goes the third
major).  Even though I have never run into a single installation that
was fully decked out with 4 boards (64 interfaces per board - I have
seen ONE that had THREE and that was scary).  Now days, I could reduce
that to 1 major (move the controls to sysfs and the raw/cooked to an
ioctl and/or sysfs) and float that.  The majors are valuable resources.
I've actually tried to give back one of those majors (the raw/cooked)
and it really can't be done for legacy reasons even as late as this,
now.  But how will this LXC config with majors and minors play with
drivers that may have different major numbers and, heavens, how do you
deal with all these USB devices and potentially varying minor numbers.
You can't, really.  Not with the current configuration scheme, you just

Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
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