softmmu/vl.c: Handle '-cpu help' and '-device help' before 'no default machine'

Currently if you try to ask for the list of CPUs for a target
architecture which does not specify a default machine type
you just get an error:

  $ qemu-system-arm -cpu help
  qemu-system-arm: No machine specified, and there is no default
  Use -machine help to list supported machines

Since the list of CPUs doesn't depend on the machine, this is
unnecessarily unhelpful. "-device help" has a similar problem.

Move the checks for "did the user ask for -cpu help or -device help"
up so they precede the select_machine() call which checks that the
user specified a valid machine type.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 16 insertions, 10 deletions

diff --git a/softmmu/vl.c b/softmmu/vl.c
index ff2685d..6a28592 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -3789,6 +3789,22 @@ void qemu_init(int argc, char **argv, char **envp)
      */
     loc_set_none();
 
+    /*
+     * Check for -cpu help and -device help before we call select_machine(),
+     * which will return an error if the architecture has no default machine
+     * type and the user did not specify one, so that the user doesn't need
+     * to say '-cpu help -machine something'.
+     */
+    if (cpu_option && is_help_option(cpu_option)) {
+        list_cpus(cpu_option);
+        exit(0);
+    }
+
+    if (qemu_opts_foreach(qemu_find_opts("device"),
+                          device_help_func, NULL, NULL)) {
+        exit(0);
+    }
+
     user_register_global_props();
 
     replay_configure(icount_opts);
@@ -3877,11 +3893,6 @@ void qemu_init(int argc, char **argv, char **envp)
         qemu_set_hw_version(machine_class->hw_version);
     }
 
-    if (cpu_option && is_help_option(cpu_option)) {
-        list_cpus(cpu_option);
-        exit(0);
-    }
-
     if (!trace_init_backends()) {
         exit(1);
     }
@@ -4112,11 +4123,6 @@ void qemu_init(int argc, char **argv, char **envp)
                       fsdev_init_func, NULL, &error_fatal);
 #endif
 
-    if (qemu_opts_foreach(qemu_find_opts("device"),
-                          device_help_func, NULL, NULL)) {
-        exit(0);
-    }
-
     /*
      * Note: we need to create block backends before
      * machine_set_property(), so machine properties can refer to