Code change produced with:
  git ls-files linux-user | \
  xargs sed -i -E 's/(\s+)printf\s*\(("Unhandled.*)\);/\1fprintf(stderr, \2);/g'
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <
20180706155127.7483-4-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
 
             arch_interrupt = false;
             break;
         default:
-            printf ("Unhandled trap: 0x%x\n", trapnr);
+            fprintf(stderr, "Unhandled trap: 0x%x\n", trapnr);
             cpu_dump_state(cs, stderr, fprintf, 0);
             exit(EXIT_FAILURE);
         }
 
             cpu_exec_step_atomic(cs);
             break;
         default:
-            printf ("Unhandled trap: 0x%x\n", trapnr);
+            fprintf(stderr, "Unhandled trap: 0x%x\n", trapnr);
             cpu_dump_state(cs, stderr, fprintf, 0);
             exit(EXIT_FAILURE);
         }
 
                     queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
                     break;
                 default:
-                    printf("Unhandled hw-exception: 0x%" PRIx64 "\n",
-                           env->sregs[SR_ESR] & ESR_EC_MASK);
+                    fprintf(stderr, "Unhandled hw-exception: 0x%" PRIx64 "\n",
+                            env->sregs[SR_ESR] & ESR_EC_MASK);
                     cpu_dump_state(cs, stderr, fprintf, 0);
                     exit(EXIT_FAILURE);
                     break;
             cpu_exec_step_atomic(cs);
             break;
         default:
-            printf ("Unhandled trap: 0x%x\n", trapnr);
+            fprintf(stderr, "Unhandled trap: 0x%x\n", trapnr);
             cpu_dump_state(cs, stderr, fprintf, 0);
             exit(EXIT_FAILURE);
         }
 
             arch_interrupt = false;
             break;
         default:
-            printf ("Unhandled trap: 0x%x\n", trapnr);
+            fprintf(stderr, "Unhandled trap: 0x%x\n", trapnr);
             cpu_dump_state(cs, stderr, fprintf, 0);
             exit(EXIT_FAILURE);
         }
 
             cpu_exec_step_atomic(cs);
             break;
         default:
-            printf ("Unhandled trap: 0x%x\n", trapnr);
+            fprintf(stderr, "Unhandled trap: 0x%x\n", trapnr);
             cpu_dump_state(cs, stderr, fprintf, 0);
             exit(EXIT_FAILURE);
         }