In what buffer the 'dmesg' messages are stored in linux?

I know the dmesg command prints the messaged stored in a ring buffer. But from the linux source code, what is the buffer's name? I want to look into the buffer after the linux is killed without any message. I suspect it's not by a software trap (hence no panic message) but I can examine the memory (with some System.map and virtual to physcial address conversion).