I couldn't resist the urge to use TLAs (three letter acronyms) to dispel the FUD (fear, uncertainty, and doubt) on my favorite topic, LE (little endian).
If you are like most customers (and my mother), the concept of data endianness rarely, if ever, enters your mind. You buy applications, operating systems, and computers. All you care is that the operating systems run your applications on the computer to accomplish your goals. If you have heard that Linux on Power is moving to little endian and are worried, your approach to survival is simple: focus on release planning details for your systems – applications, operating system, and hardware.
Who does care then about data endianness? Programmers, software vendors, hardware vendors and those 1% technology geeks who do development in the IT industry. These are the people who have noticed that the POWER8 hardware can operate with data in either big or little endian mode and for whom I wrote the “Just the FAQs about Little Endian” blog back in June. They appreciate how little endian simplifies their Linux applications running on both x86 and Power systems; they understand how little endian simplifies data sharing on disk or over the network between x86 and Power systems; and they drool over the potential of running GPUs (graphics processing units, sorry couldn't resist another TLA) on their Power Systems to create highly optimized applications common to scientific or analytic workloads.
But for the remaining 99%, what you need to know about LE can be simplified to the following key points:
Existing Linux on Power operating systems will be transitioning from BE (big endian) to LE, most likely at a major release boundary. At this boundary, the process of upgrading will involve more work than previous upgrades because the operating system and all applications will need to make the transition from BE to LE. SUSE has already announced that SLES 12 will be their transition point to LE. Red Hat shipped RHEL 7 as BE and has not announced their LE plans.
Note: Canonical will not be transitioning Ubuntu, because it started as an LE operating system.
Only POWER8 and future generations of POWER processors will be capable of running LE. As the operating system transitions on POWER7 and older systems, you will not be able to upgrade to the new LE releases. Just leave POWER7+ and older systems on the old release. If you want to run SLES 12 or Ubuntu 14.04, you will need a POWER8 system.
Hopefully you now understand that you need not learn about esoteric programming concepts as we head into the brave new world of little endian Linux on Power. Instead, as we progress through this transition, if you simply spend a little more time in planning to double check support for your applications, operating systems, and hardware during each step, you will have success. That's what I'd recommend to my mother – just a little due diligence.