code review 7389043: runtime: split minit() to mpreinit() and minit()

src/pkg/runtime/thread_freebsd.c

Index: src/pkg/runtime/thread_freebsd.c
===================================================================
--- a/src/pkg/runtime/thread_freebsd.c
+++ b/src/pkg/runtime/thread_freebsd.c
@@ -121,11 +121,19 @@
 }
 
 // Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
 void
 runtime·minit(void)
 {
 	// Initialize signal handling
-	m->gsignal = runtime·malg(32*1024);
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·sigprocmask(&sigset_none, nil);
 }