Re: GDM, getty and VTs

[Goswin von Brederlow <goswin-v-b@web.de>]

Josselin Mouette <joss@debian.org> writes:

> Le lundi 16 novembre 2009 à 13:55 +0100, Harald Braumann a écrit : 
>> > Just because it is a tradition doesnâ??t mean itâ??s the correct way.
>> So far I haven't seen any argument as to why it shouldn't be the correct
>> way.
>
> Itâ??s broken because: 
>       * there are race conditions in the way VTs are allocated; 
>       * text consoles are statically allocated, which means there are
>         too many for some users and not enough for some others; 

They are statically used without regards for allocation. Meaning if
anything allocates the tty first then the static getty just steals it
leaving the system seemingly frozen.

>       * the display manager should run on the first VT.
>
>> >       * New GDM upstream, as is, is completely broken. 
>> That seems to be the only reason. But this is clearly a bug in GDM,
>> that should be fixed there.
>
> Yes, but there are better ways to fix bugs than mimicking already
> existing bugs.
>
>> If you want X on another tty, change it in /etc/X11/xdm/Xservers. If you
>> need more ttys, add gettys to /etc/inittab. This system is so simple and
>> flexible, that I don't see how you can improve on it.
>
> Yeah, sure. Like, you know, dynamic VT allocation and X server.
>
>> So the solution is to make GDM configurable by a parameter or a config
>> file to set the vt it should start on. 
>
> You really donâ??t know what you are talking about, do you?
>
>> > I donâ??t see this as rocket science software, and it means: 
>> >       * No useless getty processes are started. 
>> I never considered this to be a real problem. 
>
> I always consider it a problem when there are unneeded processes on the
> system.
>
>> >       * tty1 is always the first VT you log on, regardless of your
>> >         setup. 
>> I don't see this as an improvement. I always want X on the same tty, no
>> matter in which order I do things. Or did I misunderstand something
>> here?
>
> X is not always on the same tty. It is only if you use an antiquity like
> xdm. Even with startx, tty allocation is dynamic.
>
>> >       * You can start an arbitrary number of text or graphical
>> > consoles, without any configuration.

How would the "Please press return to get a login" process know when
something else (like an X session) wants the tty?

>> Is this really a requirement? Where are the wishlist bugs of users
>> demanding this? And anyway, a simple script that looks for the next
>> free tty and spawns getty there solves this nice and easy.
>
> No it does not. Especially since â??looking for the next free ttyâ?? is not
> a safe operation.

Why not? What other than the getties break it?

> Cheers, 

MfG
        Goswin