On Mon, Apr 19, 2010 at 11:39:28AM +0200, Kay Sievers wrote: > On Sun, Apr 18, 2010 at 23:08, Marco d'Itri <m...@linux.it> wrote: > >> On Apr 18, Mario 'BitKoenig' Holbe <mario.ho...@tu-ilmenau.de> wrote: > >> > KERNEL=="audio", NAME="%k0", SYMLINK+="%k" > > /etc/udev/rules.d/00-local.rules > > If this specifies a name different than the kernel device name, it is > something that should be fixed.
These are my own local rules and yes, these rules specify lots of
rename-rules like the one above.
Call it obsessive (well, this is what I'm calling it sometimes :)) or
whatever you like. I personally don't like the kernel's style to threat
0-devices naming different than subsequent ones and prefer the other way
around. I was free to do this all the time from the beginning of ages
(i.e. static, fs-based /dev) up to udev 141. I always did this at my own
risk and it was never a problem. I don't want to push my opinion about
this to others, and I'm sure there are others with exactly the opposite
opinion. I'd just like to be free again :)
> > /lib/udev/rules.d/55-dm.rules
> Device-mapper is work-in-progress, and probably just uses NAME=""
> which is ok. (should still not be done that way, but it does not
> matter here).
As Marco already pointed out: NAME="mapper/$env{DM_NAME}"
> > /lib/udev/rules.d/50-udev-default.rules
> It's probably just for support of older kernels, or for deprecated
> subsystems drivers like "ieee1394", which need to be replaced by
> "firewire". There should be no rule that specifies a name that is
> different from the kernel device name.
I don't know what you exactly consider "different"... just a few
examples for you to explain which of those you consider "good" and which
"bad":
SUBSYSTEM=="bsg", NAME="bsg/%k"
SUBSYSTEMS=="usb", KERNEL=="hiddev[0-9]*", NAME="usb/%k"
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device",
NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}"
KERNEL=="capi", NAME="capi20",
KERNEL=="capi[0-9]*", NAME="capi/%n"
KERNEL=="card[0-9]*", NAME="dri/%k"
KERNEL=="hw_random", NAME="hwrng"
KERNEL=="cdemu[0-9]*", NAME="cdemu/%n"
KERNEL=="pktcdvd[0-9]*", NAME="pktcdvd/%n"
KERNEL=="cpu[0-9]*", NAME="cpu/%n/cpuid"
> > Apart from my own rules this seems to be quite a common behaviour.
> Swapping plain kernel-defined names with symlinks is not supported. It
> may work, but the behavior is undefined.
Well, this is basically the reason why in my own local rules I generally
provide symlinks from the kernel-defined names to the ones I prefer
(which triggers the bug we were talking about here :)).
> > Well, I think moving device nodes forth and back in the /dev tree is
> > quite common behavior
> Upstream udev does not really support this. Kernel device names are
> defined (and optionally created and deleted) by the kernel these days.
All right, devfs-style so to say.
regards
Mario
--
The question of whether a computer can think is no more interesting than
the question of whether a submarine can swim. -- E. W. Dijkstra
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