[sane-devel] As instructed by /etc/udev/rules.d/libsane.rules

Johannes Meixner jsmeix at suse.de
Wed Nov 18 10:01:39 UTC 2009


On Nov 17 18:53 Julien BLACHE wrote (shortened):
> Johannes Meixner <jsmeix at suse.de> wrote:
>>> That was a change in the USB layer in the kernel that needed a
>>> new/modified udev rule to create the device nodes.
>> Perhaps you misunderstood me.
>> I meant it as an example to show which awkward workarounds are needed
>> to make this thingy hopefully work for a litte bit of time (until the
>> next incompatible change happens out of a sudden).
> My point was, this particular example was *not* udev's fault BUT we got
> to see it in userspace because udev's broken by (non-)design.

This particular example _is_ udev's fault because
it is udev's fault when you see such changes in userspace.

See what Greg K-H wrote:
The kernel to userspace interface is the one that
application programs use, the syscall interface.
That interface is _very_ stable over time,

the syscall interface for udev is not stable
which is udev's fault,
there is no syscall interface for udev
which means udev cannot be used at all from userspace
so that udev is kernel internal software and accordingly
udev rules are not meant to be made by userspace
and udev rules must be provided by the udev people
so that it is again udev's fault.

By the way:
If you feel it sounds like a tiny bit of sarcasm,
you are absolutely right!

Kind Regards
Johannes Meixner
SUSE LINUX Products GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
AG Nuernberg, HRB 16746, GF: Markus Rex

More information about the sane-devel mailing list