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

Mon Jul 13 14:04:49 UTC 2020
Dmitry E. Mikhailov <d.mikhailov at infocommunications.ru>

On 7/13/20 7:03 PM, Simon Matter via CentOS-devel wrote:
> Hi,
> 
> First I suggest to move this thread over to centos list instead of
> centos-devel. I think it's more appropriate there.
Thank you. Got it.


>> 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
> 
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