Re: [LAU] RTC/HPET timer permissions

On Sun, 2012-11-25 at 03:59 -0600, Brent Busby wrote:
> Long ago, I've read many people recommending setting relaxed permissions
> on /dev/rtc for using programs like Muse, and I remember back in the
> early 2000's even seeing MPlayer requiring this and complaining on the
> console when it couldn't get it.
>
> Pretty much all distros now set default permissions of 0600 root:root on
> /dev/rtc now, and MPlayer works now anyway. Is it still necessary or
> recommended these days for proper operation of audio apps to have a
> user-accessible /dev/rtc? Is there a security risk? Do regular users
> need write access, or would a mode like 0640 root:realtime be
> sufficient?
>
> Also, I notice there is a /dev/hpet node too. Same questions apply
> there, since I would imagine HPET gives the best time of all.

Hi Brent,

I still run
sudo chgrp audio /dev/hpet ; sudo chmod g+rw /dev/hpet ; sudo modprobe snd-hrtimer
for my scripts to start audio sessions, since the question isn't what
might be or not be needed.

It's also important to be backwards compatible.

I notice that for Linux nowadays nobody does take care about this. If
application A doesn't do what it should do and does for the last years,
simply switch to application B and don't use all the important private
data of the last years any more or don't expect your scripts that set up
special conditions for some needs by e.g. stopping a service, to work
any more.

So what ever should be needed to temporarily enable hr timer usage
today, IMO it's important that it does work for your machine using alpha
software and for your 4 years old stable DAW.

2 Cents,
Ralf

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Received on Sun Nov 25 12:15:02 2012