RTThread is located in:
runtime/src/HPPA/RTThread.m3
runtime/src/SPARC/RTThread.m3
runtime/src/HP300/RTThread.m3
runtime/src/VAX/RTThread.m3
runtime/src/FreeBSD2/RTThread.m3
runtime/src/ALPHA_OSF/RTThread.m3
runtime/src/AIX386/RTThread.m3
runtime/src/DS3100/RTThread.m3
runtime/src/AP3000/RTThread.m3
runtime/src/LINUXELF/RTThread.m3
runtime/src/NEXT/RTThread.m3
runtime/src/LINUX/RTThread.m3
runtime/src/ARM/RTThread.m3
runtime/src/SUN386/RTThread.m3
runtime/src/SOLgnu/RTThread.m3
runtime/src/FreeBSD/RTThread.m3
runtime/src/SOLsun/RTThread.m3
runtime/src/IBMRT/RTThread.m3
runtime/src/SEQUENT/RTThread.m3
runtime/src/IBMR2/RTThread.m3
runtime/src/UMAX/RTThread.m3
runtime/src/IRIX5/RTThread.m3
runtime/src/SUN3/RTThread.m3
runtime/src/OKI/RTThread.m3