On 19/06/17 18:09, Laszlo Ersek wrote:
>> What seems to happen is that calling object_property_add_child() only
>> succeeds for the first instance and so a simple comparison is enough to
>> determine that the device already exists at FW_CFG_PATH. Or is this a
>> fairly terrible (ab)use of the QOM APIs?
>
> This has jogged my memory about how we ensure "at most one" for the
> vmgenid device. Please see:
>
> vmgenid_realize() [hw/acpi/vmgenid.c]
> find_vmgenid_dev() [include/hw/acpi/vmgenid.h]
>
> ... I was quite silly not to think of this on my own now, despite having
> authored commit f92063028a0e ("hw/acpi/vmgenid: prevent more than one
> vmgenid device", 2017-03-20) :/
Right that definitely helps - the following code seems to work correctly
when trying to instantiate a mixture of fw_cfg_io and/or fw_cfg_mem types:
if (!object_resolve_path_type("", TYPE_FW_CFG, NULL)) {
error_setg(errp, "at most one %s device is permitted", TYPE_FW_CFG);
return;
}
I've also copied the wording from the above commit to make everything
consistent. Does that seem okay? If so, I'll fold it into a v7 patchset.
ATB,
Mark.
