[systemd-devel] [PATCH] systemd-detect-s390-virt: add virtualization detection on s390x

[Thomas Blume]

On Mon, 7 Jul 2014, Lennart Poettering wrote:

>
> Ah! OK!
>
> Then I think a patch that simply returns a generic "s390" id for all
> s390 + s390x systems would be a good idea. i.e. when we compile for
> s390/s390x we should just return that string unconditionally, without
> checking anything else.
>
> Please prepare a patch for that, and add the new type to the
> systemd.unit(5) man page, where ConditionVirtualization= is documented.

Unfortunately, I need to pick up this topic again.
Discussing our approach with the s390 guys showed that I was lacking some
  background on the s390 PR/SM virtualization, sorry for this.

Actually, a system that is running on a logical partition (LPAR) provided by
PR/SM has access to physical hardware (except CPU).
It is true that PR/SM abstracts the hardware, but only for sharing purposes.

Details are statet at:

http://publib.boulder.ibm.com/infocenter/eserver/v1r2/topic/eicaz/eicazzlpar.htm

-->--
In other words, PR/SM transforms physical resources into virtual resources so
that many logical partitions can share the same physical resources.
--<--

Still, from the OS point of view, the shared virtual resource is real hardware.
So, I need to change the code and set ConditionVirtualization to false if the
OS runs directly on PR/SM (e.g. in an LPAR).

In this light, should we still use a common s390 _id string or would it make
sense to keep the distinction between PR/SM and z/VM?


Regards
Thomas