IBM eServer zSeries 900 Technical Guide

14 IBM eServer zSeries 900 Technical Guide

Most ESA/390 architecture instructions with 32-bit operands have new 64-bit and 32- to

64-bit analogs.

򐂰 New 64-bit branch instructions.

64-bit addressing is supported for both operands and instructions for both real addressing

and virtual addressing.

򐂰 64-bit address generation.

z/Architecture provides 64-bit virtual addressing in an address space, and 64-bit real

addressing.

򐂰 64-bit control registers.

z/Architecture control registers can specify regions, segments, or can force virtual

addresses to be treated as real addresses. The prefix area is expanded from 4K to 8K

bytes.

򐂰 New instructions provide quad-word storage consistency.

򐂰 The 64-bit I/O architecture allows CCW indirect data addressing to designate data

addresses above 2 GB for both format-0 and format-1 CCWs.

򐂰 IEEE Floating Point architecture adds twelve new instructions for 64-bit integer

conversion.

򐂰 The 64-bit SIE architecture allows a z/Architecture server to support both ESA/390 (31-bit)

and z/Architecture (64-bit) guests. Zone Relocation is expanded to 64-bit for LPAR and

z/VM.

򐂰 Use of 64-bit operands and general registers for all Cryptographic Coprocessor

instructions and Peripheral Component Interconnect Cryptographic Coprocessors and

Accelerators instructions is added.

The implementation of 64-bit z/Architecture can reduce problems associated with lack of

addressable memory by making the addressing capability virtually unlimited (16 exabytes).

Value Summary

Most of the value of the 64-bit z/Architecture is delivered by the operating system. Additional

exploitation is provided by select zSeries elements (VSAM, and others) and IBM middleware

products. Immediate benefit will be realized by the elimination of the overhead of Central

Storage to Expanded Storage page movement and the relief provided for those constrained

by the 2 GB real storage limit of ESA/390. Application programs will run unmodified on the

z900.

1.6 z900 Support for Linux

Linux and zSeries make a great team. Linux is Linux, regardless of the platform on which it

runs. It is open standards-based, supports rapid application portability, and it can be adapted

to suit changing business needs. That's why it brings access to a very large application

portfolio. zSeries enables massive scalability within a single server. Hundreds of Linux

images can run simultaneously, providing unique server consolidation capabilities and

reducing both cost and complexity.

Of course, no matter which Linux applications are brought to the zSeries platform, they all

benefit from high speed access to the corporate data that typically resides on zSeries.

To enable Linux to run on the S/390 and zSeries platform, IBM has developed and provided a

series of patches. IBM continues to support the open source community.