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List:       kde-core-devel
Subject:    Re: About realtime rights
From:       Geert Jansen <g.t.jansen () stud ! tue ! nl>
Date:       2000-07-09 23:06:07
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Stefan Westerfeld wrote:

> I'd like to have the option
>
>  ( ) Run soundserver with realtime priority
>
> more easily accessible in the future. It enables people to do medium to
> low latency tasks (such as gaming for instance) without dropouts. I'd
> like to get some feedback for this. Ultimately, I think having a
> suid-root install as default would be the best for most users.

I agree that dropouts are extremely annoying. Is it enough that the artsd 
has realtime priorities, or do the arts clients need that too?

> On the other hand, I am not very happy with the current CVS way to ensure
> (b). artswrapper does it like this:
>
> * exec'ing artsd itself - so it knows what it calls
> * having a path to artsd compiled into the artswrapper binary
> * if artsd is installed in /foo/bar/artsd, it checks that / /foo /foo/bar
> and /foo/bar/artsd is owned by root, so it can hope that it couldn't be
> modified by anyone

It should check that /dev/dsp is writable by the caller, too. If you're not 
in the correct group, or if the audio device is busy, you shouldn't be able 
to start artsd.

> All this checking behaviour isn't very comfortable for the user, so I'd
> rather have a more elegant way (if exists), or no checking at all, as in
> realtime_set.

What is uncomfortable? It seems to me that a default install will work out 
of the box, no user configuration required. If this is indeed the case, I 
would not mind having it installed suid root.

Another (very uncomfortable, but maybe some users want it) alternative is 
to have kdesu start artsd. Kdesu knows how to start up a realtime process, 
but this requires roots password. This way, no suid binaries are involved 
(except "su", of course).

Greetings,
Geert

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