Subject: Re: [linux-audio-dev] Re: RFC: real-time design.
From: Tommi Ilmonen (tilmonen_AT_cc.hut.fi)
Date: to maalis 18 1999 - 07:41:49 EST
>
> > Both require root access. If Sonic Flow were to use these, there would have to be a lot of
> >
> > security features. Eg, a block could intentionally lock up the system. The sched_setsched
>
> Would it be possible to release the root privileges after the call to
> these functions?
>
> There's some discussion on priorities on the IRIX man pages. Namely,
> it is said that digital media applications need low latency response times
> from the operating system and that changing interrupt thread behavior is
> undesirable, i.e. that priority range 110...199 should be used.
I had similar problems. I do not have root privileges on my machine and I
still need to get real-time priority.
I made a small priority control app (<200 lines) that can give priority to
my processes. That app is accessed via sudo so it has root privileges.
My app calls the sudo'ed program automatically -> Now
my app never gets the root privileges, but it does get real-time priority.
It think this is relatively secure way to go.
I can put the small app to web, but it needs some improvements to be
really usefull general purpose priority controller (right now I am the
only person it will talk to....). Besides, it works properly only in IRIX
(it uses 'ps' for certain things and the ps output format depends on
platform....)
As long as the small app has no bugs this is pretty secure solution. The
worst I could do to harm system is crash it (with busy-looping program).
Many IRIX media apps 1) start as root-privilege 2) get the resources
(priorities etc.) 3) drop the root provileges 4) Start executing the real
app.
Tommi.
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