[OE-core] [PATCH v4] systemd: set default.target to multi-user.target

[Samuel Stirtzel]

2013/4/3 Burton, Ross <ross.burton at intel.com>:
> Hi,
>
> On 2 April 2013 15:15, Samuel Stirtzel <s.stirtzel at googlemail.com> wrote:
>>>>> For xserver-nodm-init we would then have something like:
>>>>> inherit update-alternatives
>>>>> ALTERNATIVE_${PN} = "systemd-def-target"
>>>>> ALTERNATIVE_TARGET[systemd-def-target] =
>>>>> "${systemd_unitdir}/system/graphical.target"
>>>>> ALTERNATIVE_LINK_NAME[systemd-def-target] =
>>>>> "${systemd_unitdir}/system/default.target"
>>>>> ALTERNATIVE_PRIORITY[systemd-def-target] ?= "10"
>>>>>
>>>>> Signed-off-by: Radu Moisan <radu.moisan at intel.com>
>
> This really needs to be a series of two patches, with this change
> implemented too.
>
>> To comment on this change:
>> A developer would expect that a system (hardware or software) behaves
>> in a specific matter (the default behavior).
>> By changing the default, the system behavior is undefined (as the
>> default behavior was changed).
>
> The behaviour is not undefined, it's perfectly clear - the default
> target is multi-user unless changed, and by patching the X startup
> recipes in oe-core and meta-oe we handle the majority of cases.

When we decide that we handle standard behavior different than the
rest of the world, then this patch is basically a fork of systemd.
Also we tell every affected software developer:
"No your software won't work with OE-core / Yocto Project without
adaption, we are incompatible with the systemd standard to make life
more comfortable for (some of) us"


>> As alternative of changing the default I would propose that a
>> specialization overrides this symlink where needed, and the
>> generalization stays unchanged (like OOP inheritance).
>> Therefore a specialization would be image configurations or
>> postinstall appends for images that have no need for the graphical
>> user target.
>
> How would you implement this?  Register the alternative in systemd.bb
> defaulting to graphical, and then switch it in every image recipe in
> oe-core/meta-oe/etc that doesn't use an X or Wayland (patches coming
> shortly) session?

If this works why not?
It sounds like a good idea, because this way would not break anything,
and we would be compatible with the standard systemd.


>
> The bigger question to me is how to handle the alternative in a way
> that doesn't create the symlink if we're not using systemd.

I am not sure if this works, but couldn't the presence of systemd be
detected (e.g. in the image task list)?
Or alternatively the configuration of the [image|distro]-feature could
be checked (wherever systemd is usually set nowadays).


--
Regards
Samuel