S/390 Partners in Development: ThinkPad Enabled for S/390

80 S/390 PID: ThinkPad Enabled for S/390

The cu type 3172 is a defined FLEX-ES keyword and defines an LCS-type LAN connection to

S/390. (On the S/390 side, there would normally be two CTC addresses (even/odd

addresses) defined. A LAN device for use by OS/390 TCP/IP must be specified exactly as

shown (except that the device name of the interface might be different). That is, it will be

defined as two devices (00 and 01), with the second device OFFLINE. The IP address for

this interface would be specified in the OS/390 TCP/IP profile.

The device designation in this example, eth0, may appear strange to experienced UNIX

users, who will want to write something like /dev/eth0. However, eth0 worked on our

ThinkPad/EFS; furthermore, Linux does not appear to define names like /dev/eth0 or

/dev/net0.

An additional parameter may be required for a LAN definition. A “real” 3172 unit may have up

to four adapters. These are numbered 0-3, and this number appears in the OS/390 TCP/IP or

VTAM specifications.

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By default, FLEX-ES uses number zero. If you want a different

number, you must include an options statement:

R10A3088: cu 3172

options ‘adapternumber=1’

interface local(1)

device(00) 3172 eth0

device(01) 3172 OFFLINE

end R10A3088

This emulates the “real” 3172 adapter number 1. This is not related to the actual LAN adapter

number in your ThinkPad. The actual Netfinity LAN adapter that is used is specified by the

device parameter.

You can share a LAN adapter between Linux and OS/390 TCP/IPs. In order to do this, you

need to specify the IP address to be used by OS/390, as a parameter in the resource

definition. (You should specify the same address in your OS/390 TCP/IP parameters.) For

example,

R10A3088: cu 3172

options ‘ipaddress=9.12.17.211’

interface local(1)

device(00) 3172 eth0

device(01) 3172 OFFLINE

end R10A3088

Using this example, the single Ethernet adapter in our ThinkPad/EFS machine appears as IP

address 9.12.17.210 (defined when we installed Linux) and 9.12.17.211 (when we start

FLEX-ES).

Cloned devices

The FLEX-ES documentation includes an optional cloned parameter for many resources

definitions. We did not use this parameter. This parameter applies to a limited set of

devices—emulated printers and card readers are good examples—for which the resources

definitions can be automatically replicated to serve multiple S/390 instances. This is

meaningful only when multiple S/390 instances are used. It potentially saves a little time

when creating resources definitions. We suggest it may be better to take the extra time to

directly create all the resources definitions you need and ignore the cloned parameter.

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The same situation exists with a P/390 or MP3000 emulated I/O LAN adapter. It is known as the MPTS number in

these cases.