Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

denisfalqueto · 2007-07-24 00:55:16

Hi all!

I am missing /proc/sys/dev/rtc/max-user-freq to set the maximum frequency that an user app can fetch the rtc device. It seems that there is a new implementation for the rtc driver since 2.6.21. Before that (don't remember exactly when) the /proc/... was there, but now it isn't. Does anybody know how can I achieve the same result with the newer kernels?

Thanks in advance

Denis Falqueto

Last edited by denisfalqueto (2007-07-27 16:24:49)

lucke · 2007-07-24 01:27:30

You have to modprobe rtc to have that proc entry.

denisfalqueto · 2007-07-24 01:44:43

Yes, I did it, but it tells me the following:

FATAL: Error inserting rtc (/lib/modules/2.6.21-rt/kernel/drivers/char/rtc.ko): Input/output error

This kernel is from AUR, but with the ck it remains the same. Dmesg also tells me:

rtc: I/O resource 70 is not free.

It seems that there is something holding the rtc.

Some googling gave me some tips to build a kernel with the RTC compiled inside the kernel, not as a module, but I couldn't find the option in the menuconfig. I will try to rebuild this kernel with a manual configuration for the RTC.

Mefju · 2007-07-24 17:30:10

It is in Device Drivers --> Character devices --> Enhanced Real Time Clock Support

denisfalqueto · 2007-07-25 13:27:11

Yes, it worked. I compiled the kernel with the realtime patch from Ingo Molnar from AUR and enabled the rtc as sugested above inside the kernel (not as a module). Now there is back again the /proc/sys/dev/rtc/max-user-freq.

I would suggest also to the kernel-ck maintainers to do the same for that we can use this interesting feature. I found that it can help lots of applications, for example, mplayer, cd/dvd-writing and even virtualization softwares like qemu. There are dozens of tips with that in google.

Cerebral · 2007-07-26 04:11:59

denisfalqueto wrote:

Yes, I did it, but it tells me the following:
FATAL: Error inserting rtc (/lib/modules/2.6.21-rt/kernel/drivers/char/rtc.ko): Input/output error

This is caused because you've already got an rtc module modprobed - most likely rtc_cmos (which was inserted on my default setup.)

denisfalqueto · 2007-07-27 16:27:46

For the record, it was really rtc_cmos that was preventing rtc to be loaded. So, I configured rc.conf to forbid rtc_cmos and load rtc. Now the /proc/.... entry is back again.

Thanks to all!

Arch Linux

#1 2007-07-24 00:55:16

Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

#2 2007-07-24 01:27:30

Re: Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

#3 2007-07-24 01:44:43

Re: Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

#4 2007-07-24 17:30:10

Re: Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

#5 2007-07-25 13:27:11

Re: Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

#6 2007-07-26 04:11:59

Re: Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

#7 2007-07-27 16:27:46

Re: Where is /proc/sys/dev/rtc/max-user-freq? [SOLVED]

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