all class init functions for all types in QEMU are called in select_machine(). Expected?

[Claudio Fontana]

Hello Paolo and all,

while debugging a class init ordering issue, I noticed that

_all_ class init functions for all types registered in the QEMU QOM are called 
in select_machine().
Expected?

In particular it happens here:

static MachineClass *select_machine(void)
{
    GSList *machines = object_class_get_list(TYPE_MACHINE, false);


object_class_get_list() ->
  object_class_foreach() ->
    g_hash_table_foreach() ->
      object_class_foreach_tramp ->
        type_initialize(type);


Is this really desired? It looks suspect to me.

(gdb) bt
#0  0x0000555555db613f in arm_v7m_class_init (oc=0x555556dca320, 
data=0x555556a926e0 <arm_tcg_cpus+288>)
    at ../target/arm/tcg/tcg-cpu-models.c:849
#1  0x0000555555f1deba in type_initialize (ti=0x555556d5b2f0) at 
../qom/object.c:364
#2  0x0000555555f1f62a in object_class_foreach_tramp (key=0x555556d5b470, 
value=0x555556d5b2f0, opaque=0x7fffffffda20)
    at ../qom/object.c:1069
#3  0x00007ffff6562000 in g_hash_table_foreach () at /usr/lib64/libglib-2.0.so.0
#4  0x0000555555f1f709 in object_class_foreach (fn=
    0x555555f1f866 <object_class_get_list_tramp>, 
implements_type=0x555556381b09 "machine", include_abstract=false, 
opaque=0x7fffffffda70)
    at ../qom/object.c:1091
#5  0x0000555555f1f8e4 in object_class_get_list (implements_type=0x555556381b09 
"machine", include_abstract=false) at ../qom/object.c:1148
#6  0x0000555555debe94 in select_machine () at ../softmmu/vl.c:1607


If not here, where should be the right place, for example, for CPU class inits 
to be called?

At the very least I would put a comment there around the beginning of 
select_machine() saying:

/* all types, all classes in QOM are initialized here, as a result of the 
object_class_get_list call */

Wdyt?


Ciao,

Claudio



-- 
Claudio Fontana
Engineering Manager Virtualization, SUSE Labs Core

SUSE Software Solutions Italy Srl