Device categories and device drivers
There are several Linux on Z specific device categories in the /sys/devices directory.
Figure 1 illustrates a part of sysfs.
/sys/bus and /sys/devices are
common Linux directories.
The directories following /sys/bus sort the device
drivers according to the categories of devices they control. There
are several categories of devices. The sysfs branch for a particular
category might be missing if there is no device for that category.
- AP devices
- are adjunct processors used for cryptographic operations.
- CCW devices
- are devices that can be addressed with channel-command words (CCWs). These devices use a single subchannel on the mainframe's channel subsystem.
- CCW group devices
- are devices that use multiple subchannels on the mainframe's channel subsystem.
- IUCV devices
- are devices for virtual connections between z/VM® guest virtual machines within an IBM® mainframe. IUCV devices do not use the channel subsystem.
- PCI devices
- represent PCIe devices, for example, a 10GbE RoCE Express device. In sysfs, PCIe devices are listed in the /pci directory rather than the /pcie directory.
Table 1 lists the device drivers that have representation in sysfs:
| Device driver | Category | sysfs directories |
|---|---|---|
| 3215 console | CCW | /sys/bus/ccw/drivers/3215 |
| 3270 console | CCW | /sys/bus/ccw/drivers/3270 |
| DASD | CCW |
/sys/bus/ccw/drivers/dasd-eckd
/sys/bus/ccw/drivers/dasd-fba |
| SCSI-over-Fibre Channel | CCW | /sys/bus/ccw/drivers/zfcp |
| Storage class memory supporting Flash Express | SCM | /sys/bus/scm/ |
| Channel-attached tape | CCW |
/sys/bus/ccw/drivers/tape_34xx
/sys/bus/ccw/drivers/tape_3590 |
| Cryptographic | AP |
/sys/bus/ap/drivers/cex5a
/sys/bus/ap/drivers/cex5c /sys/bus/ap/drivers/cex5p /sys/bus/ap/drivers/cex4a /sys/bus/ap/drivers/cex4c /sys/bus/ap/drivers/cex4p /sys/bus/ap/drivers/cex3a /sys/bus/ap/drivers/cex3c /sys/bus/ap/drivers/pcixcc |
| DCSS | n/a | /sys/devices/dcssblk |
| XPRAM | n/a | /sys/devices/system/xpram |
| z/VM recording | IUCV | /sys/bus/iucv/drivers/vmlogrdr |
| qeth (OSA-Express features and HiperSockets ) | CCW group | /sys/bus/ccwgroup/drivers/qeth |
| LCS | CCW group | /sys/bus/ccwgroup/drivers/lcs |
| CTCM | CCW group | /sys/bus/ccwgroup/drivers/ctcm |
| NETIUCV | IUCV | /sys/bus/iucv/drivers/netiucv |
| 10GbE RoCE Express devices for Mellanox ConnectX-3 EN (mlx4_en) | PCI | sys/bus/pci/drivers/mlx4_core |
| 10 GbE RoCE Express2 devices for Mellanox ConnectX-4 EN (mlx5_core) | PCI | sys/bus/pci/drivers/mlx5_core |
Some device drivers do not relate to physical devices that are connected through the channel subsystem. Their representation in sysfs differs from the CCW and CCW group devices, for example, the cryptographic device drivers have their own category, AP.
The following sections provide more details about devices and their representation in sysfs.