16 EFS Systems on a Linux Base: Channel Adapters
definition. The names of the stanzas (chpbt0 or chpbt1 in the example) are arbitrary. The
resource stanzas specify the Linux name of each channel in the format /dev/chpbt/chx.
Every control unit FLEX-ES uses, whether emulated or real, must be precisely defined to
FLEX-ES. The device count in the cu definition must match the number of devices configured
in the control unit. This number may be more than the number of devices actually attached to
the control unit. For example, a tape control unit might have four tape drives attached but
configured for 16 in the control unit. In this case the cu statement must specify 16 devices.
Additional information is needed in the cu statements for physical channels. The exact
combinations depend on the configuration to be used. Following is the complete set of
PCA: unitadd(0x..) [interlocked] [shared] [sharedb] [streaming(20, 30, or 45)]
SCA: cuadd(0x.) unitadd(0x..) [link(0x..)]
Example 3-1 Parameter examples
cu devad(0x480,8) path(1) unitadd(0x80) interlocked shared #PCA
cu devad(0x500,16) path(1) unitadd(0x90) streaming(45) #PCA
cu devad(0x300,16) path(2) unitadd(0x00) cuadd(0x0) #SCA
cu devad(0x300,16) path(2) unitadd(0x00) cuadd(0x0) link(0xc1) #SCA
The following rules apply for the parameters:
The interlocked, shared, sharedb, and streaming parameters are needed for various IBM
parallel channel devices. Specific parameters for common devices are suggested in
Resource Language Reference, FSIMM310. (The streaming parameters 20, 30, and 45
indicate channel transfer speeds of 2.0, 3.0, and 4.5 MB/sec.)
The unitadd parameter for parallel devices is two hex digits and generally combines the
hardware address of the control unit (first digit) and the device address (second digit). The
exact usage may vary depending on the type of control unit.
The unitadd (two-hex digits) and cuadd (one-hex digit) for serial devices are the
corresponding hardware values for the control unit and devices. (These values can often
be obtained from an IOCP listing.)
The link parameter is used only when the connection is through an ESCON Director. The
parameter (two-hex digits) is the Director port number connected to the target control unit.
The devad address (first parameter, three or four-hex digits) is the device number that the
operating system sees running under FLEX-ES. In ESA mode this device number has no
relationship with the hardware control unit addresses or device addresses. All the
descriptions in this document assume the use of ESA mode.
The devad count (second parameter, usually entered as a decimal number) must reflect
the number of devices supported by the control unit. This may differ from the number of
devices actually attached to the control unit.
Please note that these parameters must match the “real” parameters of the “real” devices.
You can be creative with addresses for FLEX-ES emulated devices; however, that is not the
case for the unitadd, cuadd, link, and device count parameters. These parameters reflect
actual hardware characteristics of external units. The devad address parameter, which sets
the address used by software under FLEX-ES, is not determined by external hardware and
can be anything desired by the user.
Important: This requirement is important! An incorrect cu definition for physical channels
can lead to obscure problems later.
This statement assumes we are in XA mode where the device number (“software address” or “address”) is not
related to hardware addresses.