This is concerning /dev/ttyS* (and probably /dev/ttyUSB*, too): udev-070 sets (in /etc/udev/rules.d/50-udev.rules) the group ownership for serial ports to "tty". /sbin/MAKEDEV (from baselayout-1.12.0_pre8-r2) sets the group ownership for these ports to "dialout". 1. This is clearly inconsistent. 2. As far as I understand, the purpose of the "tty" group is to allow programs such as write(1) and wall(1) access other users' terminals. 3. One probably does not want to include users directly in the "tty" group. If they need access to serial lines, the should be members of the "dialout" group. (Long time ago, this would have been group "uucp".) Please change the default group ownership for serial lines in udev to "dialout".
As a cross issue please see Bug #108088. Also consider using uucp as the group for historical reasons.
MrNess explained the reasons that he doesn't want to change the group for /dev/ttyS?? to dialout; there is no gaurantee that it will be a modem. I then inquired about why the dialout group was there at all and he said "that group is used by slmodem for example, when it creates the device file" so it won't go away either. The only thing left is to change the baselayout's call to /sbin/MAKEDEV so that it also creates the device with the tty group ownership.
This is not a udev issue, please open a new bug for baselayout if you wish to have MAKEDEV change groups.
One final note. Bug reporter (Ulrich), please see Bug #28407 for why things are like they are. The problem, as most people perceive it here, is that someone dared to question the number one cardinal rule which says, | "Gentoo developers are never wrong." | Considering the age of Bug #28407, most of the information in there is devfs specific and outdated now, but the basic "ttyS??" problem is still the same and most likely will never change. The reasons may have changed, though. Last year, allegedly users needed R/W access to serial ports so they can use their serial mice. It even used to be in the installation handbook that all users have to be in group "tty" (although the real reason turned out to be insufficient permissions on "/dev/ptmx", that prevented users from opening ptys, see also Bug #53086 and Bug #53292). And just to show who's boss, after someone discovered MAKEDEV got it right, MAKEDEV was changed so it creates ptmx mode 660 too. Sadly, here we've come to the conclusion it's best to never mention it, because bug reports on that very subject usually turned out to make things worse (Yes, for all other Linuxes serial ports are group "uucp", or "dialup" for Debian, noone else uses "tty", udev or static, for very good reasons, group "tty" is for something entirely different). Thanks, __rnz__
(In reply to comment #4) Rainer, thanks for pointing to bug #28407. Obviously, I agree with your view on the tty group in bug #28407 comment #22. However, I believe it will not help if we start mixing factual with personal or emotional arguments. Lets _please_ stick to the facts. The /dev/ptmx issue has been fixed, see bug #108250. Finally, I agree with Greg that the serial port issue is not udev specific and that the discussion should therefore be continued in bug #108249.
