[systemd-devel] systemd does not shutdown system, it is waiting for a serial tty to show up

Hans de Goede hdegoede at redhat.com
Tue Mar 17 07:12:58 PDT 2015


On 16-03-15 20:41, David Herrmann wrote:
> Hi
> On Mon, Mar 16, 2015 at 7:32 PM, Hans de Goede <hdegoede at redhat.com> wrote:
>> Hi,
>> On 16-03-15 18:12, David Herrmann wrote:
>>> Hi Hans
>>> On Mon, Mar 16, 2015 at 5:15 PM, Hans de Goede <hdegoede at redhat.com>
>>> wrote:
>>>> Hi,
>>>> On some of the ARM boards I work on in my spare time I've
>>>> done "systemctl enable getty at ttyGS0.service" to get a getty
>>>> on the usb gadget serial port which I've configured on the
>>>> devices otg controller.
>>>> This serial port device node /dev/ttyGS0 shows up as soon
>>>> as the gadget serial port driver loads, but is only usable
>>>> when I plug in a the mini B end of a mini B -> A usb cable
>>>> where the A end is plugged into an active usb host.
>>>> "ps aux" shows something peculiar here, when I do "ps aux"
>>>> before the cable is plugged in it shows "(agetty)" in
>>>> the args column of the output, when I then plug in the
>>>> cable the output changes to "/sbin/agetty --noclear ttyGS0 vt220"
>>>> note this is the same process, as before the cable was plugged,
>>>> I've a feeling that somehow the process is stuck halfway
>>>> exec or some such ... ??
>>> We rename the process to "(<file>)" directly after fork(). So if it is
>>> still "(agetty)", something blocks before we can exec(). Can you run
>>> strace to figure out what call blocks?
>> strace -p<pid> says:
>> write(3, "\33[r\33[H\33[2J", 10
> Ok, this is vt_disallocate() running, which reminded me that you have
> to use serial-getty at .service for serial ttys. getty at .service is only
> for VTs. Can you check whether this solves your issues?

Yes that seems to solve my issue, I say seems because I've only done
a few quick test, but it looks good sofar.



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