Say for example I were to take the hard drive of my LFS build and put it in a different computer. Granted, I'll need to generate a new kernel based on the different hardware but what about the differences in CPUs?

Say I go from an old single core AMD Athlon to a multi-core intel i7 chip? Does everything else also need to be recompiled? Are these binaries I compiled using chip specific registers?

Just curious.

Depends I suppose on the compiler options you have use to build the system and how different the two systems are, if you have used a lot of arch dependent optimizations you may run into anything from kernel panics to seg faults to just odd failures, best bet is just to 'suck it and see'.

Distros that are designed to run on a number of different machines even of the same basic architechture are quite complex an not heavily optimized, which is one of the main reasons I use LFS because I can tailer it to my individual machine.

Thanks for the info. As I look through the LFS book, I don't think I see any arch dependent optimizations. I'm not savvy enough to deviate from the book without it breaking anything.

But when it comes to ./configure, it looks like some very specific information. I wander if that is capable of identifying and using CPU specific optimizations.

configure is mostly concerned with deciideing what needs to be linked with, compiled and what needs to go where doesn't really affect the arch specific compilation, ( except in special cases ) too much, of course the further along you go with lfs/blfs tje more hardware problems you are going to run into, video and network are going to be your major causes of concern.

To able to run LFS in any system you should build kernel with i686 option for 32bit system and generic x86_64 for 64bit system.

Build packages with i686-pc-linux-gnu for 32bit systems ad x86_64-unknown-linux-gnu for 64 bit systems.

Don't use a gcc -march compiler option specific to a system for example avoid 'athlon-xp'. Also check that some packages may use this specific cpu model option -march while building. Look logs of build output and build a correct one with generic cpu like i686 for 32 bit ones (for 64bit ones there is no such generic option; just don't let -march option while building.

For more info on sub-model-options see 'info gcc'.

Also try build a generic kernel with modules supporting each and every hardware. Use it as a reserve. After booting a different system with generic kernel, you can rebuild a kernel with modules for only that specific hardware.