[LAU] /dev/rtc permissions on Debian

[Jeremy Jongepier]

On 01/08/12 19:50, R. Mattes wrote:
> On Sun, 08 Jan 2012 19:14:39 +0100, rosea.grammostola wrote
>> On 01/08/2012 12:40 AM, James Stone wrote:
>>> On 1/7/12, rosea.grammostola<rosea.grammostola at gmail.com>   wrote:
>>>> Hi,
>>>>
>>>> cannot set tick on /dev/rtc permission denied
>
> What a unhelpful error message! can't they at least include information
> on the value that was supposed to be used?
>
>>
>> same here, but the audio group has also the rights for /dev/rtc
>
> We need the permissions of the actual device file (/dev/rtc0) , _not_
> the link since the link permission only describes who is allowed to
> follow the link.
>
>> But still I get the message when launching Oostudio (openoctave /
>> oom).
>
> You might have your settings for the maximum value set too low. What does
> the following show:
>
>   $ cat /sys/class/rtc/rtc0/max_user_freq
>
> On older kernels that should be:
>
>   $ cat /proc/sys/dev/rtc/max-user-freq
>
> Also relevant:
>
>   $ cat /proc/sys/dev/hpet/max-user-freq
>
> You can set these values like this:
>
>   $ sudo echo 2048>  /sys/class/rtc/rtc0/max_user_freq
>   $ sudo echo 2048>  /proc/sys/dev/hpet/max-user-freq
>
> or set them in /etc/sysctl.conf
>
> HTH Ralf Mattes
>

Hello,

How does this all relate to the snd-hrtimer ALSA module? Or is this a 
software timer while hpet and rtc0 are hardware timers? This is a bit 
uncharted territory for me and I like to get things straight for the 
LinuxMusicians system configuration page 
(http://wiki.linuxmusicians.com/doku.php?id=system_configuration), and 
also for myself as I use MIDI a lot (Qtractor, seq24, Hydrogen etc.).

Best,

Jeremy