不论是rt0_go还是go语法(如果在有idle的状况下)最终都会调用mstart
mstart
// mstart is the entry-point for new Ms.//// This must not split the stack because we may not even have stack// bounds set up yet.//// May run during STW (because it doesn't have a P yet), so write// barriers are not allowed.////go:nosplit//go:nowritebarrierrecfunc mstart() { _g_ := getg() osStack := _g_.stack.lo == 0 if osStack { // Initialize stack bounds from system stack. // Cgo may have left stack size in stack.hi. // minit may update the stack bounds. // // Note: these bounds may not be very accurate. // We set hi to &size, but there are things above // it. The 1024 is supposed to compensate this, // but is somewhat arbitrary. size := _g_.stack.hi if size == 0 { size = 8192 * sys.StackGuardMultiplier } _g_.stack.hi = uintptr(noescape(unsafe.Pointer(&size))) _g_.stack.lo = _g_.stack.hi - size + 1024 } // Initialize stack guard so that we can start calling regular // Go code. _g_.stackguard0 = _g_.stack.lo + _StackGuard // This is the g0, so we can also call go:systemstack // functions, which check stackguard1. _g_.stackguard1 = _g_.stackguard0 mstart1() // Exit this thread. if mStackIsSystemAllocated() { // Windows, Solaris, illumos, Darwin, AIX and Plan 9 always system-allocate // the stack, but put it in _g_.stack before mstart, // so the logic above hasn't set osStack yet. osStack = true } mexit(osStack)}