3 files changed, 10 insertions, 3 deletions
diff --git a/hw/timer/i8254_common.c b/hw/timer/i8254_common.c
index dc2196c1ef..9db5c9d129 100644
--- a/hw/timer/i8254_common.c
+++ b/hw/timer/i8254_common.c
@@ -282,7 +282,12 @@ static void pit_common_class_init(ObjectClass *klass, void *data)
 
     dc->realize = pit_common_realize;
     dc->vmsd = &vmstate_pit_common;
-    dc->cannot_instantiate_with_device_add_yet = true; /* FIXME explain why */
+    /*
+     * Reason: unlike ordinary ISA devices, the PIT may need to be
+     * wired to the HPET, and because of that, some wiring is always
+     * done by board code.
+     */
+    dc->cannot_instantiate_with_device_add_yet = true;
 }
 
 static const TypeInfo pit_common_type = {
diff --git a/hw/timer/m48t59.c b/hw/timer/m48t59.c
index e079d41818..3cfb18a8b3 100644
--- a/hw/timer/m48t59.c
+++ b/hw/timer/m48t59.c
@@ -750,9 +750,10 @@ static void m48t59_isa_class_init(ObjectClass *klass, void *data)
     DeviceClass *dc = DEVICE_CLASS(klass);
 
     dc->realize = m48t59_isa_realize;
-    dc->cannot_instantiate_with_device_add_yet = true; /* FIXME explain why */
     dc->reset = m48t59_reset_isa;
     dc->props = m48t59_isa_properties;
+    /* Reason: needs to be wired up by m48t59_init_isa() */
+    dc->cannot_instantiate_with_device_add_yet = true;
 }
 
 static const TypeInfo m48t59_isa_info = {
diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c
index ad61e2cffb..6fb124fead 100644
--- a/hw/timer/mc146818rtc.c
+++ b/hw/timer/mc146818rtc.c
@@ -899,9 +899,10 @@ static void rtc_class_initfn(ObjectClass *klass, void *data)
     DeviceClass *dc = DEVICE_CLASS(klass);
 
     dc->realize = rtc_realizefn;
-    dc->cannot_instantiate_with_device_add_yet = true; /* FIXME explain why */
     dc->vmsd = &vmstate_rtc;
     dc->props = mc146818rtc_properties;
+    /* Reason: needs to be wired up by rtc_init() */
+    dc->cannot_instantiate_with_device_add_yet = true;
 }
 
 static const TypeInfo mc146818rtc_info = {