qdev: Replace no_user by cannot_instantiate_with_device_add_yet

In an ideal world, machines can be built by wiring devices together
with configuration, not code.  Unfortunately, that's not the world we
live in right now.  We still have quite a few devices that need to be
wired up by code.  If you try to device_add such a device, it'll fail
in sometimes mysterious ways.  If you're lucky, you get an
unmysterious immediate crash.

To protect users from such badness, DeviceClass member no_user used to
make device models unavailable with -device / device_add, but that
regressed in commit 18b6dad.  The device model is still omitted from
help, but is available anyway.

Attempts to fix the regression have been rejected with the argument
that the purpose of no_user isn't clear, and it's prone to misuse.

This commit clarifies no_user's purpose.  Anthony suggested to rename
it cannot_instantiate_with_device_add_yet_due_to_internal_bugs, which
I shorten somewhat to keep checkpatch happy.  While there, make it
bool.

Every use of cannot_instantiate_with_device_add_yet gets a FIXME
comment asking for rationale.  The next few commits will clean them
all up, either by providing a rationale, or by getting rid of the use.

With that done, the regression fix is hopefully acceptable.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel.a@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

4 files changed, 4 insertions, 4 deletions

diff --git a/hw/isa/isa-bus.c b/hw/isa/isa-bus.c
index 9e104eb..6b2114d 100644
--- a/hw/isa/isa-bus.c
+++ b/hw/isa/isa-bus.c
@@ -197,7 +197,7 @@ static void isabus_bridge_class_init(ObjectClass *klass, void *data)
     DeviceClass *dc = DEVICE_CLASS(klass);
 
     dc->fw_name = "isa";
-    dc->no_user = 1;
+    dc->cannot_instantiate_with_device_add_yet = true; /* FIXME explain why */
 }
 
 static const TypeInfo isabus_bridge_info = {
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index 19b2198..c1ca4d4 100644
--- a/hw/isa/lpc_ich9.c
+++ b/hw/isa/lpc_ich9.c
@@ -644,7 +644,7 @@ static void ich9_lpc_class_init(ObjectClass *klass, void *data)
     dc->reset = ich9_lpc_reset;
     k->init = ich9_lpc_initfn;
     dc->vmsd = &vmstate_ich9_lpc;
-    dc->no_user = 1;
+    dc->cannot_instantiate_with_device_add_yet = true; /* FIXME explain why */
     k->config_write = ich9_lpc_config_write;
     dc->desc = "ICH9 LPC bridge";
     k->vendor_id = PCI_VENDOR_ID_INTEL;
diff --git a/hw/isa/piix4.c b/hw/isa/piix4.c
index 1a1d451..d9dac61 100644
--- a/hw/isa/piix4.c
+++ b/hw/isa/piix4.c
@@ -113,7 +113,7 @@ static void piix4_class_init(ObjectClass *klass, void *data)
     k->device_id = PCI_DEVICE_ID_INTEL_82371AB_0;
     k->class_id = PCI_CLASS_BRIDGE_ISA;
     dc->desc = "ISA bridge";
-    dc->no_user = 1;
+    dc->cannot_instantiate_with_device_add_yet = true; /* FIXME explain why */
     dc->vmsd = &vmstate_piix4;
 }
 
diff --git a/hw/isa/vt82c686.c b/hw/isa/vt82c686.c
index 5fb8086..b06d15e 100644
--- a/hw/isa/vt82c686.c
+++ b/hw/isa/vt82c686.c
@@ -480,7 +480,7 @@ static void via_class_init(ObjectClass *klass, void *data)
     k->class_id = PCI_CLASS_BRIDGE_ISA;
     k->revision = 0x40;
     dc->desc = "ISA bridge";
-    dc->no_user = 1;
+    dc->cannot_instantiate_with_device_add_yet = true; /* FIXME explain why */
     dc->vmsd = &vmstate_via;
 }