Today I compile the RTAI on the new computer which has 4 cores.
I find a good tutorial "How to Install RTAI in Ubuntu Hardy" .
I do it by that guided book.
Three parts need to be changed:
1, In the kernel configure menu, I need turn off "cpu idle PM management" and select ACPI and deselect APM).
2,In the RTAI configure menu, I need set"General > Linux source tree =/usr/src/linux".Not the headers directory.
3, Add path" /usr/realtime/bin " to the environment. I need add the command to /home/usrname/.bashrc or /root/.bashrc.(like "export PATH=$PATH:/usr/realtime/bin")