Red Hat ENTERPRISE LINUX 3 - FOR IBM S-390 AND IBM ESERVER ZSERIES, Руководство по установке

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Appendix F. Additional Information
for S/390 and zSeries Users
1. The
sysfs
File System
The Linux 2.6 kernel introduces the
sysfs
file system. The
sysfs
file system is described as a
union of the
proc
,
devfs
, and
devpty
file systems. The
sysfs
file system enumerates the
devices and busses attached to the system into a file system hierarchy that can be accessed
from user space. It is designed to handle the device and driver specific options that have
previously resided in
/proc/
, and encompass the dynamic device addition previously offered by
devfs
. At this early point in the implementation of
sysfs
, there are many drivers and utilities
that still refer to the older
proc
entries. However, it is understood that
sysfs
is the way of the
future.
The
sysfs
file system is mounted at
/sys/
and contains directories that organize the devices
attached to the system in several different ways. The
/sysfs/
subdirectories include:
1. The
/devices/
directory
This directory contains the
/css0/
directory. Its subdirectories represent all the subchannels
detected by the Linux kernel. Subchannel directories are named in the form
0.0.nnnn
where
nnnn
is the subchannel number in hex between 0 and ffff. Subchannel directories in turn
contain status files and another subdirectory which represents the actual device. The device
directory is named
0.0.xxxx
where
xxxx
is the unit address for the device. The
/devices/
directory also contains status information as well as configuration options for the device.
2. The
/bus/
directory
This contains a
/ccw/
subdirectory and a
/ccwgroup/
subdirectory. CCW devices are
accessed using channel command words. Devices in the
/ccw/
directory only use one
subchannel on the mainframe channel subsystem. CCW group devices are also accessed
with channel command words, but they use more than one subchannel per device. For
example, a 3390-3 DASD device uses one subchannel, while a QDIO network connection for
an OSA adapter uses three subchannels. The
/ccw/
and the
/ccwgroup/
directories both
contain directories called devices and drivers:
The
/devices/
directory contains a symbolic link to the device directories in the
/sys/devices/css0/
directory.
The
/drivers/
directory contains directories for each device driver currently loaded on the
system. The
zFCP
driver has a directory here. The
/driver/
directory contains settings for
the device driver, as well as symbolic links to the devices it is using (in the
/sys/devices/css0/
directory).
3. The
/class/
directory
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