Lunar Linux:FAQ

These are the Frequently Asked Questions for Lunar Linux. You have a question about Lunar? You might get your answer below.

General

What is Lunar Linux?

What exactly is Lunar Linux?

Answer:

• Please read up on it at "About"
  
  

Optimizations

how do I set these optimizations?

how do I set these optimizations?

Answer: just run lunar optimize. You'll be taken through an interactive menu that explains all the options. Remember, optimize safely!

What are the recomended safe optimizations for lunar linux?

What are the recomended safe optimizations for lunar linux?

Answer: The default sure fire optimizations that are recommended are:

• C: -pipe
• C++: -pipe
• CPU Architecture: you should pick __your__ own system architecture (default to x86 for most people).
• Basic Optimzations: Fast (-01) but most people will opt in for Faster, or Fastest (fastest doesn't work on all systems, i.e. k6).
• CPU: Obviously your own cpu, or the cpu of the machine you plan to run this install on. (If you want to be able to run this install on many machines, you should be safe with I586).
• Speed Optimizations: If you want to be 100% sure that there won't be optimization problems you shouldn't select any of these.
• Extra features: I wouldn't recomend using any of these optimizations (only on modules know to be able to handle them), since they cause many apps to break.
• Floating Point Math: None (if your arch is x86 and you don't own a 386SX and 486SX, it's safe to go with x387).
• Linker options: Strip.
• Addon program support: CCache (make sure to install it first).

NOTE: These settings should work for almost everyone, and there is a lot room for pushing these optimizations more (at the risk of problems with apps). Read "info gcc" and make sure you understand a given optimization BEFORE you enable it!

What optimizations are known to cause problems?

What optimizations are known to cause problems?

Answer: Some optimizations that are known to cause problems on x86 with many apps (even a entire system):

• -funroll-loops
• -fstrict-aliasing
• -ffast-math
• -ffloat-store

NOTE: These are sorted from the least unstable to most unstable. Read "info gcc" and make sure you understand a given optimization BEFORE you enable it!

What optimizations can I use to gain some speed but without major risks?

What optimizations can I use to gain some speed but without major risks?

Answer: Start with the basic optimizations in the question "What are the recomended safe optimizations for lunar linux?" and change the Basic Optimizations to Faster (Fastest if you know that gcc will generate correct code for that cpu). -O2 obviously takes more compile time than -O1, and -O3 takes the most time to compile. Then select the cpu you will run it on. Some of the speed optimizations that should be decent and shouldn't cause too many problems (if any) are: -fomit-frame-pointer. A safe bet for floating point math on a x86 would be x387 (if you know your cpu has a floating point unit). Check "cat /proc/cpuinfo" to see if your cpu supports SSE or SSE2. If your cpu does have sse or sse2 then you can also add that to the math optimizations.

NOTE: Your results may vary. Read "info gcc" and make sure you understand a given optimization BEFORE you enable it!

What optimizations should I stay away from?

What optimizations should I stay away from?

Answer: All the ones listed in the Question "What optimizations are known to cause problems?" plus:

• -fprofile-arcs
• -fbranching-probabilities

Note:Read "info gcc" and make sure you understand a given optimization BEFORE you enable it! The Lunar-Devs have no sympathy for bug-reports of the nature "Why can't I compile a given module, when my optimizations are: (long list of UNSAFE optimizations!!!)"