On Tue, 2004-07-06 at 18:17 +0200, Owen Taylor wrote:
On Tue, 2004-07-06 at 22:28, Jeremy Katz wrote: The value of it on the case of the writable root filesystem is that you only have one path for how the system works, not two. Changes to device naming only have to be put into one place. Eventually we can simple drop the dev package and it's 18,000 files.
But exactly what does the 18k files cost it? Similarly, we could drop ldconfig runs in %post and just have all of the symlinks created on each boot, but that doesn't strike me as a good idea either. It's a useful optimization to have them laid down by the install because then you never have to create new device nodes. Which can be a lot of device nodes per device. Changes to device naming is simple -- just make what gets used for the creation the same as what gets used in the dev package's spec file. Nice and simple to do with current infrastructure.
The less we have to modify the root file-system in our normal configuration, the less "weird" the diskless case is.
One tweak in /etc/sysconfig/foo doesn't seem overkill -- it could even be something that's used for more than one thing (as I'm fairly certain there will have to be other things that happen slightly different in the diskless case)
Plus we can't get away from the fact that /dev really is a dynamic system. Even if we ignore hotplug, we are modifying the permissions on it for the console user stuff. As such writing these changes to disk across reboots is wrong.
I disagree. We'll just agree to disagree here.
My bigger concern is that udev has _zero_ policy. It basically is a "well, we want to let people do what they want" system. Which is no better than doing nothing at all. And then, when you try to put it into initrds, you have to allow the full range of shell utilities which is just absurdity. If we're willing to say "this is our policy, if you change it, you get to make changes to other things too so that they keep working", that's fine and then udev could be almost reasonable (although I still think it's overkill)
There's a lot of other components of our system which are absurdly over-configurable in ways that would badly break the system - the X init scripts, the init scripts, gdm, etc, etc. Isn't turning over-configurability into a working system one of the main OS-assembly tasks?
Yes, but does that mean that we should add more overly configurable bits when something far simpler would suffice?
Clearly there has to be a policy about how devices are named; it's just one of the things that has to be there for a stable usable system. Having a simple C program that can read a policy description file and name devices would certainly be vastly more efficient way of doing things than all the shell scripts that udev runs.
Except that with what udev currently allows, you can't do so with one C program... because everyone wants a different way to do it.
But udev exists now, and that's a big advantage for it.
Existence doesn't necessarily make something the best solution to a problem. In cases with significant architectural impact on the system, it's far better to take a little bit longer and get a better technical solution than to throw in something just because it's there. I'll just point to the file choose in gtk as an example here :-)
Jeremy