Comment 21 for bug 794315

Is it a prerequisite?

It was done in the past so there is a strong argument that is should continue.

If it is Ubuntu policy that '~/.profile' get sourced by the display manger, all the display managers should do it and the sample file should not indicate it is intended for the login shell.

Which indicates to me I should not expect '~/.profile' to get sourced if a display manager is handling the login or if I am starting one shell from another shell.

If it is not policy then various places where these things are documented should give more complete information on when you should expect it to work.

https://help.ubuntu.com/community/EnvironmentVariables

Gives the expectation it should work...

But right after they link to

http://userbase.kde.org/Session_Environment_Variables/en

Which does not say anything about '/etc/profile' or '~/.profile'.

So should I take it that I should not expect kdm to source these files or is the sole purpose of the link to give you additional KDE specific options?

And I don't see on the community documentation page anyting about '~/.xsessionrc' (Debian) or '~/.xprofile' (Redhat).

Should we expect one or both of these to work and should we expect them to continue working in the future with Mir and Wayland?

More discussion there than should be had in a bug report for lightdm, presenting them here so the questions are out there for future thought.