On Tue, 9 Aug 2016, update wrote:

>On booting a new installed xenial with trinity tdm I get the error message:
>"A start job is running for Hold until boot process finishes up(time/no limit)" which prevents starting the console logins.
>Using sddm or lightdm works together with systemd.
>I have looked into the systemd configuration of them both and changed the file
>/lib/systemd/system/tdm.service according to the sddm configuration to
>
>[Unit]
>Description=Trinity Display Manager
>Documentation=man:tdm-trinity(1)
>Conflicts=getty@...
>After=getty@...
>
># Ordering
>Conflicts=plymouth-quit-wait.service
>After=systemd-user-sessions.service plymouth-start.service plymouth-quit-wait.se
>OnFailure=plymouth-quit.service
>
>[Service]
># temporary safety check until all DMs are converted to correct
># display-manager.service symlink handling
>ExecStartPre=/bin/sh -c '[ "$(basename $(cat /etc/X11/default-display-manager 2>
>ExecStart=/opt/trinity/bin/tdm
>Restart=always
>RestartSec=1s
>
>With this file the plymouth/systemd handshake seams to work.
>
>Maybe this helps someone else.

Maybe...  I hope so...
I had the same boot "freeze" here on xenial:
"A start job is running for Hold until boot process finishes up(time/no limit)"
I did not connect it with trinity tdm.  Googling show me folks with the
same issue -- but different causes/fixes -- none of which worked in my case.
Perhaps my problem is/was what you explain above.
What I did was remove systemd and go back to upstart.
If time permits and my frustration level stays low, I may try your fix, Stef.
I am still trying to beat several (other) problems into submission after
upgrading to Ub 16.04.

Thanks for your report!
Jonesy
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