[PATCH v2 1/1] modules: Improve error message when module is not found

[Jose R. Ziviani]

When a module is not found, specially accelerators, QEMU displays
a error message that not easy to understand[1]. This patch improves
the readability by offering a user-friendly message[2].

This patch also moves the accelerator ops check to runtine (instead
of the original g_assert) because it works better with dynamic
modules.

[1] qemu-system-x86_64 -accel tcg
ERROR:../accel/accel-softmmu.c:82:accel_init_ops_interfaces: assertion failed:
(ops != NULL)
Bail out! ERROR:../accel/accel-softmmu.c:82:accel_init_ops_interfaces:
assertion failed: (ops != NULL)
    31964 IOT instruction (core dumped)  ./qemu-system-x86_64 ...

[2] qemu-system-x86_64 -accel tcg
accel-tcg-x86_64 module is missing, install the package or config the library 
path correctly.

Signed-off-by: Jose R. Ziviani <jziviani@suse.de>
---
 accel/accel-softmmu.c |  5 ++++-
 util/module.c         | 14 ++++++++------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/accel/accel-softmmu.c b/accel/accel-softmmu.c
index 67276e4f52..52449ac2d0 100644
--- a/accel/accel-softmmu.c
+++ b/accel/accel-softmmu.c
@@ -79,7 +79,10 @@ void accel_init_ops_interfaces(AccelClass *ac)
      * all accelerators need to define ops, providing at least a mandatory
      * non-NULL create_vcpu_thread operation.
      */
-    g_assert(ops != NULL);
+    if (ops == NULL) {
+        exit(1);
+    }
+
     if (ops->ops_init) {
         ops->ops_init(ops);
     }
diff --git a/util/module.c b/util/module.c
index 6bb4ad915a..268a8563fd 100644
--- a/util/module.c
+++ b/util/module.c
@@ -206,13 +206,10 @@ static int module_load_file(const char *fname, bool 
mayfail, bool export_symbols
 out:
     return ret;
 }
-#endif
 
 bool module_load_one(const char *prefix, const char *lib_name, bool mayfail)
 {
     bool success = false;
-
-#ifdef CONFIG_MODULES
     char *fname = NULL;
 #ifdef CONFIG_MODULE_UPGRADES
     char *version_dir;
@@ -300,6 +297,9 @@ bool module_load_one(const char *prefix, const char 
*lib_name, bool mayfail)
 
     if (!success) {
         g_hash_table_remove(loaded_modules, module_name);
+        fprintf(stderr, "%s module is missing, install the "
+                        "package or config the library path "
+                        "correctly.\n", module_name);
         g_free(module_name);
     }
 
@@ -307,12 +307,9 @@ bool module_load_one(const char *prefix, const char 
*lib_name, bool mayfail)
         g_free(dirs[i]);
     }
 
-#endif
     return success;
 }
 
-#ifdef CONFIG_MODULES
-
 static bool module_loaded_qom_all;
 
 void module_load_qom_one(const char *type)
@@ -384,4 +381,9 @@ void qemu_load_module_for_opts(const char *group) {}
 void module_load_qom_one(const char *type) {}
 void module_load_qom_all(void) {}
 
+bool module_load_one(const char *prefix, const char *lib_name, bool mayfail)
+{
+    return false;
+}
+
 #endif
-- 
2.32.0