On 29/10/2025 08.52, Philippe Mathieu-Daudé wrote:
QOM .instance_init() handler can not fail. QDev DeviceRealize
can.

The device-introspect QTest enumerates all QDev types and
instantiate each one, without realizing it, then introspects
the instance properties.

When switching to a single QEMU binary, all QDev types are
available in the binary, but only a filtered subset might be
available, depending on which previous target the binary is
trying to mimic.

In particular with the Raspi machines, the TYPE_RASPI4B_MACHINE
and ARM_CPU_TYPE_NAME("cortex-a72") will be built in the
qemu-system-arm binary, while not available (because filtered
as being 64-bit, for the qemu-system-aarch64 binary).

However the TYPE_BCM2838 SoC is not filtered out, and will
abort when being initialized, because the "cortex-a72" CPU type
is filtered out, leading to device-introspect failure:

   1/1 qemu:qtest+qtest-arm / qtest-arm/device-introspect-test        ERROR     
       2.46s   killed by signal 6 SIGABRT
   stderr:
   unknown type 'cortex-a72-arm-cpu'
   Broken pipe
   ../../tests/qtest/libqtest.c:199: kill_qemu() tried to terminate QEMU 
process but encountered exit status 1 (expected 0)
   (test program exited with status code -6)
   TAP parsing error: Too few tests run (expected 167, got 5)

In order to avoid that, move the CPU *initialization* in the
SoC DeviceRealize handler, so the SoC initialization won't
fail, while realization still will.

Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
---
  hw/arm/bcm2836.c | 10 +++++-----
  1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/hw/arm/bcm2836.c b/hw/arm/bcm2836.c
index cd61ba15054..6e4066f137d 100644
--- a/hw/arm/bcm2836.c
+++ b/hw/arm/bcm2836.c
@@ -25,12 +25,7 @@ static void bcm283x_base_init(Object *obj)
  {
      BCM283XBaseState *s = BCM283X_BASE(obj);
      BCM283XBaseClass *bc = BCM283X_BASE_GET_CLASS(obj);
-    int n;
- for (n = 0; n < bc->core_count; n++) {
-        object_initialize_child(obj, "cpu[*]", &s->cpu[n].core,
-                                bc->cpu_type);
-    }
      if (bc->core_count > 1) {
          qdev_property_add_static(DEVICE(obj), 
&bcm2836_enabled_cores_property);
          qdev_prop_set_uint32(DEVICE(obj), "enabled-cpus", bc->core_count);
@@ -65,6 +60,11 @@ bool bcm283x_common_realize(DeviceState *dev, 
BCMSocPeripheralBaseState *ps,
      BCM283XBaseClass *bc = BCM283X_BASE_GET_CLASS(dev);
      Object *obj;
+ for (int n = 0; n < bc->core_count; n++) {
+        object_initialize_child(OBJECT(dev), "cpu[*]", &s->cpu[n].core,
+                                bc->cpu_type);
+    }
+
      /* common peripherals from bcm2835 */
obj = object_property_get_link(OBJECT(dev), "ram", &error_abort);

Reviewed-by: Thomas Huth <[email protected]>


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