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The default css 0xfe is currently restricted to virtual subchannel
devices. The hope when the decision was made was, that non-virtual
subchannel devices will come around when guest can exploit multiple
channel subsystems. Since the guests generally don't do, the pain
of the partitioned (cssid) namespace outweighs the gain.
Let us remove the corresponding restrictions (virtual devices
can be put only in 0xfe and non-virtual devices in any css except
the 0xfe -- while s390-squash-mcss then remaps everything to cssid 0).
At the same time, change our schema for generating css bus ids to put
both virtual and non-virtual devices into the default css (spilling over
into other css images, if needed). The intention is to deprecate
s390-squash-mcss. With this change devices without a specified devno
won't end up hidden to guests not supporting multiple channel subsystems,
unless this can not be avoided (default css full).
Let us also advertise the changes to the management software (so it can
tell are cssids unrestricted or restricted).
The adverse effect of getting rid of the restriction on migration should
not be too severe. Vfio-ccw devices are not live-migratable yet, and for
virtual devices using the extra freedom would only make sense with the
aforementioned guest support in place.
The auto-generated bus ids are affected by both changes. We hope to not
encounter any auto-generated bus ids in production as Libvirt is always
explicit about the bus id. Since
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| .. | ||
| 3270-ccw.h | ||
| adapter.h | ||
| css-bridge.h | ||
| css.h | ||
| ebcdic.h | ||
| event-facility.h | ||
| ioinst.h | ||
| s390_flic.h | ||
| s390-ccw.h | ||
| s390-virtio-ccw.h | ||
| sclp.h | ||
| storage-attributes.h | ||
| storage-keys.h | ||