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I want to install an RPM package, but I'm not sure whether to install the x86_64 or i386 version. WHM says CENTOS 6.5 i686 virtuozzo at the top.

How can I determine which version to install?

arash yousefi
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Nate
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4 Answers4

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A quick overview of architecture names for x86 systems:

  • i386: The 80386 CPU has historically been the bare minimum for running Linux on a PC-compatible system. Consequently, a package for "i386" is designed for maximum compatibility and can run on any x86-like system; a system that describes itself as "i386" is either ancient or exotic, and can only be counted on to run i386 packages.
  • i485, i586: Rarely-seen, these refer to the 80486 and Pentium (80586) CPUs. Almost nobody builds packages specifically for them, targeting either i386 or i686 instead.
  • i686: This is the "P6" microarchitecture, used by Intel for the Pentium Pro and newer. It's generally considered the baseline for "modern" 32-bit x86 systems. An "i686" package is designed to run on these systems (and will usually perform better than a "i386" version); an "i686" system can run any i386, i486, i586, or i686 package.
  • x86_64: This is the 64-bit instruction set for x86 CPUs. An "x86_64" package can only run on x86_64 systems; an "x86_64" system requires special kernel and library support (which almost all mainstream Linux distros provide) to run packages from the i*86 family.

You've got an "i686" system, so given the choice between "i386" and "x86_64", you want the "i386" version.

Mark
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  • And you should add this list is read from the bottom up: you start the bottom until you hit your system's architecture, and you go up until you hit a package architecture. Kind of. – Calimo Jul 27 '14 at 07:50
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In this case, use the i386 (or 32-bit) package.

ewwhite
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    Why? You answer ought to provide support or reasoning. – Sled Jul 25 '14 at 21:07
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    @ArtB Well, this is because the x86_64 package (64-bit) won't run on a 32-bit platform. – ewwhite Jul 25 '14 at 21:11
  • Correct me if I'm wrong, but isn't this why it's x86? For the various numbers that could go in the x position? – jpmc26 Jul 25 '14 at 23:37
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    @jpmc26 but the choices are i386 and *x86_64*, note the **_64** meaning "64 bit". He's running *i686* which is not 64-bit so i386 is the proper choice. – Josh Jul 26 '14 at 03:32
  • @Josh ?? I think you misunderstood my comment. I was saying that x86 describes the series of processors architectures than end in 86. So i386 is one of them, where the x is filled in by the 3. – jpmc26 Jul 26 '14 at 03:36
  • I am still not understanding @jpmc26. Yes, *x86* is used to denote "processor architectures ending in 86", but the two choices he has available are one package specifically compatible with 386 processors, and one package compatible with x86 64-bit processors. I don't understand what you mean by, "but isn't this why it's x86?" – Josh Jul 26 '14 at 03:55
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You can simply use the "arch" command in order to have your answer.

Zatarra
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You need the 32-bit (i.e. the i386) package as the "i686" report shows that you're running a 32-bit platform.

As a general rule, if you're not sure of the destination platform, get the 32-bit build, as a 64-bit platform can run a 32-bit image, but not the other way around.

Gwyn Evans
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