Emulated S/390 | | | |
running OS/390 | | other Linux | |
and its normal | | |
| processes | |
applications | | |
| | |
| | FLEX-ES | |
FLEX-ES processes | | Terminal Solicitor | |
| | |
| | | ThinkPad |
| | | display and |
| | TCP/IP | keyboard |
| | |
Linux | operating | system | Windows |
| | |
PC Processor in ThinkPad | |
| | Enet Adapt | |
ThinkPad disks | | | |
| | LAN | |
Figure 3-1 Conceptual view of FLEX-ES system
Key points include:
FLEX-ES is a software product.2 All the hardware shown (in Figure 3-1)is standard ThinkPad hardware.
The FLEX-ES program, running under Linux on the ThinkPad’s PC processor, emulates a complete S/390 environment.
–FLEX-ES obtains sufficient virtual memory to emulate the “real memory” for the defined S/390 machine being emulated. While not detailed in the illustration, FLEX-ES can also emulate expanded memory.
–FLEX-ES, as part of emulating a S/390, handles S/390 I/O instructions and emulates the S/390 I/O devices as required. In the illustration, various 3390 volumes (containing OS/390 and so forth) are contained on the ThinkPad disks.
The FLEX-ES license specifies how many PC processors may be used (at any one instant) for S/390 emulation. For a ThinkPad/EFS system this will normally be one processor.
The owner can elect to dedicate PC processor(s) to FLEX-ES S/390 use. This provides a performance boost. You cannot dedicate all the PC processors to S/390, because other Linux functions need access to a processor. If processors are not dedicated, then the normal Linux dispatching function will dictate which processors are being used by FLEX-ES at any instant. The number will never exceed the number permitted in the FLEX-ES license. A ThinkPad/EFS system has only a single PC processor, and it cannot be dedicated for S/390 emulation.
2The optional S/390 channel adapters available for use with FLEX-ES are ignored in this discussion.
Chapter 3. FLEX-ES and OS/390 installation 17
