[LAU] RTC/HPET timer permissions

Brent Busby brent at keycorner.org
Sun Nov 25 09:59:54 UTC 2012


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.

-- 
+ Brent A. Busby	 + "We've all heard that a million monkeys
+ Sr. UNIX Systems Admin +  banging on a million typewriters will
+ University of Chicago	 +  eventually reproduce the entire works of
+ James Franck Institute +  Shakespeare.  Now, thanks to the Internet,
+ Materials Research Ctr +  we know this is not true." -Robert Wilensky


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