[Qemu-devel] [PATCH] qom/object: Display more helpful message when an object type is missing

[Philippe Mathieu-Daudé]

When writing a new board, adding device which uses other devices
(container) or simply refactoring, one can discover the hard way
his machine misses some devices. In the case of containers, the
error is not obvious:

  $ qemu-system-microblaze -M xlnx-zynqmp-pmu
  **
  ERROR:/source/qemu/qom/object.c:454:object_initialize_with_type: assertion 
failed: (type != NULL)
  Aborted (core dumped)

And we have to look at the coredump to figure the error:

  (gdb) bt
  #1  0x00007f84773cf895 in abort () at /lib64/libc.so.6
  #2  0x00007f847961fb53 in  () at /lib64/libglib-2.0.so.0
  #3  0x00007f847967a4de in g_assertion_message_expr () at 
/lib64/libglib-2.0.so.0
  #4  0x000055c4bcac6c11 in object_initialize_with_type (address@hidden, 
address@hidden, type=<optimized out>) at /source/qemu/qom/object.c:454
  #5  0x000055c4bcac6e6d in object_initialize (address@hidden, address@hidden, 
address@hidden "xlnx.zynqmp_ipi") at /source/qemu/qom/object.c:474
  #6  0x000055c4bc9ea474 in xlnx_zynqmp_pmu_init (machine=0x55c4bdd46000) at 
/source/qemu/hw/microblaze/xlnx-zynqmp-pmu.c:176
  #7  0x000055c4bca3b6cb in machine_run_board_init (machine=0x55c4bdd46000) at 
/source/qemu/hw/core/machine.c:1030
  #8  0x000055c4bc95f6d2 in main (argc=<optimized out>, argv=<optimized out>, 
envp=<optimized out>) at /source/qemu/vl.c:4479

Since the caller knows the type name requested, we can simply display it
to ease development.

With this patch applied we get:

  $ qemu-system-microblaze -M xlnx-zynqmp-pmu
  qemu-system-microblaze: missing object type 'xlnx.zynqmp_ipi'
  Aborted (core dumped)

Since the assert(type) check in object_initialize_with_type() is
now impossible, remove it.

Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
 qom/object.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/qom/object.c b/qom/object.c
index e3206d6799e..b1ba62c5b9e 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -28,6 +28,7 @@
 #include "qapi/qmp/qbool.h"
 #include "qapi/qmp/qnum.h"
 #include "qapi/qmp/qstring.h"
+#include "qemu/error-report.h"
 
 #define MAX_INTERFACES 32
 
@@ -451,7 +452,6 @@ static void object_initialize_with_type(void *data, size_t 
size, TypeImpl *type)
 {
     Object *obj = data;
 
-    g_assert(type != NULL);
     type_initialize(type);
 
     g_assert(type->instance_size >= sizeof(Object));
@@ -471,6 +471,11 @@ void object_initialize(void *data, size_t size, const char 
*typename)
 {
     TypeImpl *type = type_get_by_name(typename);
 
+    if (!type) {
+        error_report("missing object type '%s'", typename);
+        abort();
+    }
+
     object_initialize_with_type(data, size, type);
 }
 
-- 
2.20.1