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Re: [Qemu-devel] QOM: Can devices having link properties be user-creatab
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-devel] QOM: Can devices having link properties be user-creatable? |
Date: |
Fri, 12 Oct 2018 15:06:39 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
On 12/10/2018 15:01, Peter Maydell wrote:
> On 12 October 2018 at 13:47, Philippe Mathieu-Daudé <address@hidden> wrote:
>> While looking at Mao's series
>> (https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg02519.html) I
>> wondered if devices having link properties can be user-creatable.
>>
>> Using the following patch (I don't think this is correct to put qdev
>> code into qobject, but I used this as PoC):
>>
>> -- >8 --
>> diff --git a/qom/object.c b/qom/object.c
>> index 547dcf97c3..2dd3a25531 100644
>> --- a/qom/object.c
>> +++ b/qom/object.c
>> @@ -16,4 +16,5 @@
>> #include "qom/object_interfaces.h"
>> #include "qemu/cutils.h"
>> +#include "qemu/error-report.h"
>> #include "qapi/visitor.h"
>> #include "qapi/string-input-visitor.h"
>> @@ -1662,4 +1663,11 @@ void object_property_add_link(Object *obj, const
>> char *name,
>> gchar *full_type;
>> ObjectProperty *op;
>> + ObjectClass *klass = object_get_class(obj);
>> +
>> + if (klass && object_dynamic_cast(obj, TYPE_DEVICE) &&
>> + DEVICE_CLASS(klass)->user_creatable == false) {
>> + warn_report("Device type '%s' is user_creatable "
>> + "(linked property: '%s')", type, name);
>> + }
>>
>> prop->child = child;
>> ---
>>
>> I get:
>>
>> $ aarch64-softmmu/qemu-system-aarch64 -M virt
>> qemu-system-aarch64: warning: Device type 'bus' is user_creatable
>> (linked property: 'parent_bus')
>> qemu-system-aarch64: warning: Device type 'qemu:memory-region' is
>> user_creatable (linked property: 'memory')
>
> Is your warning printing the wrong thing? "bus", "irq",
> etc don't seem like names of devices...
Oh indeed I inverted (type, name) :)
> I think whether a device with a link property is
> user creatable might depend on what the property is
> for and whether the device has a useful fallback for
> "link not connected".
OK it now makes sens, reading this example:
static void bcm2836_realize(DeviceState *dev, Error **errp)
{
Object *obj;
Error *err = NULL;
obj = object_property_get_link(OBJECT(dev), "ram", &err);
if (obj == NULL) {
error_setg(errp, "%s: required ram link not found: %s",
__func__, error_get_pretty(err));
return;
}
...
Thanks!
Phil.