LXRT: Fix cpu selection

Author: Hannes Diethelm

src/rtapi/uspace_rtai.cc

@@ -81,15 +81,18 @@ struct RtaiApp : RtapiApp {
     static void *wrapper(void *arg) {
         auto task = reinterpret_cast<RtaiTask*>(arg);
         pthread_setspecific(key, arg);
-        task->rt_task = rt_task_init(task->id, task->prio, 0, 0);
-        rt_set_periodic_mode();
-        start_rt_timer(nano2count(task->period));
-        if(task->uses_fp) rt_task_use_fpu(task->rt_task, 1);
+        
+        int nprocs = sysconf( _SC_NPROCESSORS_ONLN );
+        int cpus_allowed = 1 << (nprocs-1); //Use last CPU as default
         const static int rt_cpu_number = find_rt_cpu_number();
         if(rt_cpu_number != -1) {
             rtapi_print_msg(RTAPI_MSG_INFO, "rt_cpu_number = %i\n", rt_cpu_number);
-            rt_set_runnable_on_cpus(task->rt_task, 1u << rt_cpu_number);
+            cpus_allowed = 1 << rt_cpu_number;
         }
+        task->rt_task = rt_task_init_schmod(task->id, task->prio, 0, 0, SCHED_FIFO, cpus_allowed);
+        rt_set_periodic_mode();
+        start_rt_timer(nano2count(task->period));
+        if(task->uses_fp) rt_task_use_fpu(task->rt_task, 1);
         rt_make_hard_real_time();
         rt_task_make_periodic_relative_ns(task->rt_task, task->period, task->period);
         (task->taskcode) (task->arg);

src/rtapi/uspace_rtapi_app.cc

@@ -1087,7 +1087,7 @@ int find_rt_cpu_number() {
         if(CPU_ISSET(i, &cpuset)) top = i;
     }
     if(top == -1){
-        rtapi_print_msg(RTAPI_MSG_ERR, "No isolated CPU's found, expect some latency!");
+        rtapi_print_msg(RTAPI_MSG_ERR, "No isolated CPU's found, expect some latency or set RTAPI_CPU_NUMBER to select CPU\n");
     }
     return top;
 #else