[systemd-devel] unable to create bridge name "default"

[William Tu]

On Thu, Mar 30, 2017 at 8:55 AM, Lennart Poettering
<lennart at poettering.net> wrote:
> On Sat, 11.03.17 08:41, William Tu (u9012063 at gmail.com) wrote:
>
>> Hi,
>> I'm not sure if this is caused by systemd-udev, apology if it's not
>> the right place. When doing
>> # brctl addbr default
>> add bridge failed: Invalid argument
>
> If brctl fails with EINVAL, then this suggests that the kernel refuses
> this already, and udev is not involved. Please ping the
> bridging/networking community.
>
> Lennart
>
> --
> Lennart Poettering, Red Hat

Hi Lennart,
Thanks for your reply. I've found out that it is indeed kernel refuses
"default" name of the netdev. By executing "brctl addbr default" and
tracing the kernel source, it shows "default" isn't allowed in one of
the netdev notifier, a call stack is below if anyone is interested:
  sysctl_dev_name_is_allowed
    devinet_sysctl_register
      inetdev_event
        notifier_call_chain
          raw_notifier_call_chain
            call_netdevice_notifiers_info
              register_netdevice
                register_netdev
                  br_add_bridge

Regards,
William