I have "rtc" in /etc/modules but
ERROR: modinfo: could not find module rtc
and lsmod doesn't show rtc
The legacy real-time-clock driver
but I believe it's only used in the module context as an include while building modules for specific RTC devices. For example, here's the rtc drivers available for Ubuntu's Linux kernel 3.2:
izx@i5:~/src-kernel$ ls /lib/modules/3.2.0-24-generic/kernel/drivers/rtc/ rtc-88pm860x.ko rtc-ds1742.ko rtc-max6900.ko rtc-rs5c372.ko rtc-ab3100.ko rtc-ds3232.ko rtc-max6902.ko rtc-rv3029c2.ko rtc-ab8500.ko rtc-ds3234.ko rtc-max8925.ko rtc-rx8025.ko rtc-bq32k.ko rtc-em3027.ko rtc-max8998.ko rtc-rx8581.ko rtc-bq4802.ko rtc-fm3130.ko rtc-mc13xxx.ko rtc-s35390a.ko rtc-ds1286.ko rtc-isl12022.ko rtc-msm6242.ko rtc-stk17ta8.ko rtc-ds1305.ko rtc-isl1208.ko rtc-pcf2123.ko rtc-v3020.ko rtc-ds1307.ko rtc-m41t80.ko rtc-pcf50633.ko rtc-wm831x.ko rtc-ds1374.ko rtc-m41t93.ko rtc-pcf8563.ko rtc-wm8350.ko rtc-ds1390.ko rtc-m41t94.ko rtc-pcf8583.ko rtc-x1205.ko rtc-ds1511.ko rtc-m48t35.ko rtc-r9701.ko rtc-ds1553.ko rtc-m48t59.ko rtc-rp5c01.ko rtc-ds1672.ko rtc-m48t86.ko rtc-rs5c348.ko
As Florian asked, why do you need this module? What is your platform? Are you using a specific RTC device?
You can safely remove
There is no kernel module named
Why do you think there should be such a module? What do you want to do?
There are a couple of rtc drivers built statically into the Ubuntu kernel. Namely rtc_cmos and rtc_m41t80. (I have /dev/rtc and /dev/rtc0 on my 12.04 system, by the way.) rtc_cmos supports the legacy PC cmos real time clock. The other certain i2c real time clocks.
The config file for each built Ubuntu kernel is placed into /boot along with the headers and the kernel image itself so you can see how it was set up.
Built in drivers don't show up in lsmod, for example.
At one time there was a driver simply named rtc, but not now. I'd suggest that some package places that name in /etc/modules.
The Ubuntu kernel source is here.