-cpu Questions

[Harold Grovesteen]

I am brand new to qemu for s390x.  Installed it from the Ubuntu
package.  As output from qemu-system-s390x executable:

QEMU emulator version 6.2.0 (Debian 1:6.2+dfsg-2ubuntu6.5)

Just trying to familiarize myself with Qemu.  Did a few helps (qemu -h,
machine help, cpu help).

Tried to run -cpu z13.2.  Produced a long list of unavailable features.
Tried to run -cpu z14.2.  Produced another long list, but not
identical, list of unavailable features.

Tried -cpu max and all of the unavailable features disappeared,
apparently now available to -cpu max, although two warnings resulted.

Four questions...

Why is a full list of features supported by -cpu max but not -cpu z13.2
or -cpu z14.2?

If the features are present (which they obviously are because -cpu max
finds them), why are z13.2 and z14.2 not finding them (but obviously
are aware of them)?

Is this an artifact of using the Ubuntu package version of qemu s390x
vs. a build from scratch?

Additionally, most cpu's would apparently correspond to individual
hardware models.  What is the significance of genxx cpu models?

Thank you for your assistance...

Harold Grovesteen