0TB (Old Tech Bloke) says in his EXCELLENT video Slackware 15: Easy Slackbuild Management With Helper Applications:I have been using Linux for more than 10 years,Slackware regularly for at least 3 years, but I am a true distro-hopper so I haven’ t gone deep anywhere. My understanding of the underlying logic of systems is extremely limited.

In this case I was surprised by OTB’s comment because I felt it challenged (demolished ?) one of the few understandings I believed I had, namely that when one compiles a package it is compiled in a somehow optimal way to some architecture/hardware configuration.

This has been my motivation to try to learn about compiling, as I can not afford modern powerful machines. I always hope to extract best performance by choice of software and optimization of its installation.

I am hoping that OTB has many ThinkPads of the same model and that that is why he can install multiple times from one compilation. But my instinct which is far superior to my logic suggests that I may be in for some sad news which is why I am posting this here so that I may get some final understanding with your kind help.

I run Slackware64-15.0 on 3 different machines, all x86_64 architecture, and keep them up-to-date so the package base is the same across those. When I build custom/third party software, I build it on my fastest machine and then installpkg there and on the other machines. This works fine because its built/linked against the same libraries on any of these machines. Perhaps this is what "OTB" meant?

I try to be careful and use a clean/up-to-date slackware chroot when building packages to distribute across multiple machines so I can avoid linking against differing third party libraries, since my build machine has more custom software on it than the others. However, if they are all the same then it shouldn't matter.

If you build on something like slackware-current and then install that package on slackware-15.0, then you will run into problems from being built against different libraries.

If you build and install on different architectures then things dont work at all. E.g. Building a x86_64 package and installing it on aarch64 will fail.

HTH

Edit: Perhaps you are thinking of kernels? Those can be optimized for differing hardware configurations. However, the generic and huge kernels are designed to work across a wide variety of configurations and work for most cases.

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When you compile a program you tell the compiler how much to optimize. Slackware’s packages are compiled once but can run on all x86_64 computers (speaking of Slackware 64, obviously). This is because the optimization flags used when compiling tell the compiler to target all x86_64 CPUs (basically target the lowest/oldest x86_64 CPU). For 32-bit Slackware you’ll see lots of packages with i686 in the name - meaning they won’t run on i386 - i586 CPUs.

If you want, you can use the -march=native flag to tell the compiler to target the CPU of the computer doing the compiling. Such a program compiled this way will most likely not run on older CPUs. I think Gentoo does this for lots of packages in an attempt to eek out as much performance as possible.

Roughly speaking newer CPUs only add features (instruction sets), not take them away. So programs compiled for older CPUs should run on newer CPUs.

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Spend some time studying the -march and -mtune options and it should all become clear

https://gcc.gnu.org/onlinedocs/gcc/x...ml#x86-Options

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Officially, Slackware is built to run on ia-32 and x86_64 based processors.

Any binaries compiled by you on a particular version/edition of Slackware will be compatible with any other computer running the same version/edition of Slackware.

That is to say, for example: Any program compiled using Slackware64-15.0 will run on any other computer running Slackware64-15.0.

This is part of the reason that a full installation of Slackware is (highly!) recommended. It ensures that you're using the same libraries as everyone else, and on all of your machines. If you want to "compile once and use everywhere," then you can... just like OTB does.

It's also a major point of difference between Slackware and most other distributions... in that most other distributions don't have a standardised set of packages, so you can't be sure that the same libraries exist on all of your machines.

Slackware comes with everything that was used to build it. Nothing is kept from you.

EDIT: This is also the reason why I prefer to run the stable release and not 'current'... the libraries in 'current' can be "shifting sands."

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If you want to run highly optimized code, then you should be using Gentoo, not Slackware. Gentoo was named after the fastest-swimming penguin in the world! Not only is all code compiled locally, but you can set all kinds of flags for the compilations to ensure that you are getting the last drop out of your system. Me, I can't be arsed. I use Slackware because Slackware just works.

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I am so glad I came here for help!

It feels like my problem has been through (a successfull) psychanalysis.

You went all on spot. I guess Gentoo was close to come to my mind, but I was so focused on my questions that I never allowed it.

I explain: I had a swift and happy introduction into Linux through Mint which remained my only distro for about 4 years.

I was then mentored by the IT-administrator at the school I worked who gave me an old i-mac G3 with 346Mb ram and an outdated macOS, and told me about Gentoo and the possibility of trimming it.

And that was really the ultimate cause for my questiom.

I spent three years reading and trying to install Gentoo on that machine, successfully and easily installed Lubuntu and Debian, but could not use them - too slow.

I did install Gentoo on an old HP but after I accidentally nuked it I could not install the newer versions, concluded that the machine was possibly too old and at the same time realized I am not smart enough to work with Gentoo. I do not have the patience and discipline to go through an n-curse configuration with over 6000 items.

Then I found Sabayon which became my favorite until its tragic end. After that I tried many different distros but kept coming back to the Slackware website because I was fascinated with the little I understood of it. Took me one or two years before I dared trying it. It has not been easy, but it sure feels way more comfortable than Gentoo, and I have had fantastic support all the way.

So Hazel is right, I should use Gentoo. But I simply can’t. And Slackware has been working fine for me.

I still don’t really fully understand most of what I read about operational systems, I just have some fuzzy intuitive understanding, but it has worked so far even if it could become much better.

So your answers have helped me understand Slackware better. I had been missing many interesting points. Like :

I had never imagined this would be possible.

I was also totally unaware of this.

I am now wondering if there is any sense in compiling packages for which there are binaires available in BobAlien’s repo. Will be thankful for opinions on this.


I am pretty sure I won’t resist taking a look at that sooner or later. I know it means trouble, but thanks for the link.

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The convenience of AlienBob's repo is the fact that he compiles all these programs already. If you have an x86_64 machine, then install from his x86_64 repo. This particularly nice for something like his DAW suite of software; it would take quite a while to compile all the parts manually. Same thing for his massive VLC build.

You should be leery of installing prebuilt packages from random places on the internet, but AlienBob has an excellent reputation and maintains an open dialog with users so I trust his packages (my opinion, of course).

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I am still using Gentoo and I can tell that hardware optimizations mattered more few years ago than they matter now. Compilers are just smarter so actual gains aren't as big as few years ago.
However unless all your boxes are almost identical optimization gain will be negligible.
Gentoo is very nice though and might be more popular this days if not for the hurdle with system installation (of course one can accept defaults but what's point of it?).

If you want speed then compile RT kernel. It will cut compile time 50% - 75% percent.

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This is true for 99% of all software out there. However, some software, during the configuration step, might check the features of your current CPU and optimize its configuration against that CPU. Then you might end up with binaries requiring specific instructions like SSE4 or avx2 and end up with "illegal instruction" when trying to run on an older CPU lacking those instructions.

The architecture part of the Slackware package name (like i586 or x86_64) is not very specific when it comes to details about different generations of CPU architectures.

regards Henrik

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