[Qemu-devel] [PATCH RFC 9/9] qdev: Do not let the user try to device_add when it cannot work

[armbru@redhat.com]

From: Markus Armbruster <armbru@redhat.com>

Such devices have always been unavailable and omitted from the list of
available devices shown by device_add help.  Until commit 18b6dad
silently broke the former, setting up nasty traps for unwary users,
like this one:

    $ qemu-system-x86_64 -nodefaults -monitor stdio -display none
    QEMU 1.6.50 monitor - type 'help' for more information
    (qemu) device_add apic
    Segmentation fault (core dumped)

I call that a regression.  Fix it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qdev-monitor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qdev-monitor.c b/qdev-monitor.c
index 36f6f09..c538fec 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -477,7 +477,7 @@ DeviceState *qdev_device_add(QemuOpts *opts)
         }
     }
 
-    if (!obj) {
+    if (!obj || DEVICE_CLASS(obj)->cannot_instantiate_with_device_add_yet) {
         qerror_report(QERR_INVALID_PARAMETER_VALUE, "driver", "device type");
         return NULL;
     }
-- 
1.8.1.4