IBM 88554RU Installation Guide - Page 167

Data type in C long double LP32 128 LP64 128 Keep these comparisons in mind while programming or porting applications to any 64-bit operating system, not only Linux. It is easy to assume that every data type is the same size, and that is why the LP Data Model standard was created. Note: The LP64 Data Model example discussed in this publication is not the only 64-bit Data Model defined by The Open Group. There are other models, such as LP64, ILP64, or LLP64 for 64-bit; and ILP32 or LP32 for 32-bit. For more information about the data models defined by The Open Group and also about their standardization activities, go to: http://www.opengroup.org Byte order The IA-64 kernel of Linux also uses standard byte order at a byte level. The native byte order is little-endian, while big-endian processes are still possible. All Intel processors are little-endian based. That means that the bytes at lower addresses have lower significance given a 16-bit or 32-bit word (the word is stored "little-end-first"). In big-endian architectures, the bytes addresses have higher significance (the word is stored "big-end-first"). The IA-64 Linux kernel uses little-endian by default, but allows for the possibility of using big-endian byte order. 4.4.2 Choosing a Linux distribution Unlike other operating systems, when we talk about Linux, we are not talking about one company, one version, or one distributor. Linux is the kernel, the base of the system, and there are many companies that develop Linux distributions built around the kernel. In this section we discuss the major Linux distributors that work with IBM, and their different products available for the Itanium 2 platform: Red Hat and UnitedLinux. Note that the IBM Linux support page is: http://www.pc.ibm.com/qtechinfo/MIGR-48NT8D.html Here you can find information about the Linux distributions supported by IBM, and documents, information, and drivers for IBM products. Chapter 4. Installation 153