RTC: Only single RAM bank (128 bytes)... What is that?

[dodamn]

I'm using Snow Leopard 10.6.0 64bit.
There is no kernel panic in booting.

Today, I saw dmesg message. And there is 'RTC: Only single RAM bank (128 bytes)' in the message.

What does that mean?
Is it error message?
And how to fix it?

My mobo has 2 ram slots. And eash has a 2GB memory. So total 4GB.

Thank you.