[CentOS-devel] NFSroot over wifi in CentOS 7 - graceful shutdown problem

Hi,

First I suggest to move this thread over to centos list instead of
centos-devel. I think it's more appropriate there.

> Hi,
>
> I've got a task to have a small number of laptops netboot Linux over
> WiFi. The kernel is loaded off the USB stick of cource, it's off topic
> for now.
>
> The WPA-supplicant daemon is started early by dracut off initrd. It
> works. Mostly.
>
> The problem is that upon shutdown systemd terminates all the processes
> FIRST and unmounts filesystems NEXT.
>
> Guess what? Upon termination, wpa-supplicant brings the wireless
> interface down and the system hangs being unable to unmount now-defunct
> NFSroot.

What I'm wondering here is, do you see the hangs because of wpa_supplicant
was terminated and therefore also the wireless interface is down, or do
you see the hangs because networking is already completely down.

If it is because wpa_supplicant gets terminated, then maybe it would be
possible to terminate wpa_supplicant in a way that it lets the wireless
interface still up and functional at least for a certain amount of time.

I don't know wpa_supplicant good enough but I think maybe it is not always
needed to be alive for the wireless interface to work.

Otherwise, I guess it's more a question for the systemd developers than
for CentOS or Linux in general.

Regards,
Simon