Subchannel attributes

Red Hat Enterprise Linux 9.2 LPAR mode z/VM guest KVM guest

There are sysfs attributes that represent subchannel properties, including common attributes and information specific to the subchannel type.

Subchannels have two common attributes:
type
The subchannel type, which is a numerical value, for example:
  • 0 for an I/O subchannel
  • 1 for a CHSC subchannel
  • 3 for an EADM subchannel
modalias
The module alias for the device of the form css:t<n>, where <n> is the subchannel type (for example, 0 or 1).
These two attributes are the only ones that are always present. Some subchannels, like I/O subchannels, might contain devices and further attributes.
Apart from the bus ID of the attached device, I/O subchannel directories typically contain these attributes:
chpids
is a list of the channel-path identifiers (CHPIDs) through with the device is connected.
dev_busid
the device bus-ID of the associated device. For subchannels with no associated device, the value is none.
pimpampom
provides the path installed, path available, and path operational masks. See z/Architecture® Principles of Operation, SA22-7832 for details about the masks.