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

David Herrmann dh.herrmann at gmail.com
Mon Mar 16 10:12:36 PDT 2015

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?

Furthermore, what state is the process in?


> If I plug in the cable I get a getty on the other end of
> the usb gadget serial connection and everything more or less
> works. I say more or less because it seems that part of
> the welcome header from getty gets lost, and sometimes getty
> acts as if it has received some garbage on its stdin. I mention
> this because it may be related, but it may also very well be a
> bug in the usb stack somewhere.
> The problem which I have why I'm sending this mail is that
> halt (-p) or reboot does not work when there is no usb cable
> plugged into the otg connector.
> "halt -p" just sits there for a long time, and then exits with
> a dbus timeout error. If I plug in the cable while it is doing
> this, then it continues and starts shutting down.
> Regards,
> Hans
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