Should I install Gentoo i586 packages on my PC? [closed]

Question

I've recently commenced revitalizing an HP Pavilion Slim. She's running an Intel Pentium, x86_64. I thought I'd give Gentoo a go because I've found it very appealing and as a Bedrock user I wanted to be able to boot off of Gentoo's init system (initrc, we all know why) as well as bootloader. I've gotten almost halfway through the install ( maybe more like a third :))) ), and now I'm looking for the stage3 files for my PC. I've noticed that though there are builds for i486 and i686. Being genuinely interested in which my PC was, I searched it up and after some light digging found this explanation:

• i386 works with any x86 processor (Intel, AMD,etc.),
• i486 has some performance tun[n]ing.
• i586 for Pentium and Pentium-MMX
• i686 for Pentium-Pro, P2,P3, P4, etc.

[source]

But in that case Gentoo doesn't support my device?!? Hence, my question: what i version (?) is my Intel Pentium PC? And where are the stage3 files for it? Is it possible to use, say, an i486 for a presumed i586?

Answer 1

The original Pentium, which succeeded the i80486, was indeed the original definition of the i586 instruction set - and not x86_64. But the Pentium was introduced in 1993, and your HP machine is much newer than that. Intel has continued to use the Pentium brand for almost every x86-compatible CPU line they've made since then, to great confusion among people not intimately familiar with the history.

As a brief summary:

• 8088, 8086, 80286, 80386, 80486 are all pre-Pentium
• Pentium Classic (aka P5, defined i586)
• Pentium MMX
• Pentium Pro (aka P6, defined i686)
• Pentium II
• Pentium III (introduced SSE)
• Pentium 4 (aka NetBurst, introduced SSE2)
• Pentium M (for laptops)
• Core series, which itself has gone through many versions.

Since the Core series was introduced, Intel now uses the Pentium and Celeron branding for low-end and often severely cut-down versions of Core series processors.

The Pentium G-series is one of these cut-down Core series CPUs, does support x86_64, and is really too new to ask the Retrocomputing SE about. I will simply recommend you to install the amd64 version of Gentoo rather than the i586 or i686 builds.

For anyone who actually has a Pentium Classic, Pentium-MMX, or other genuine i586 device, Gentoo doesn't have an i586 stage build, but the i486 build will work. You can then rebuild it optimised for i586 and the specific CPU that you have. Expect it to take some time, on the order of weeks, as these CPUs are very old and slow.

Answer 2

Gentoo is a source-based distribution, where everything is built from the source. You can tune GCC to build for i586 like this:

COMMON_FLAGS="-march=i586 -mtune=pentium -O2 -pipe"

in your /etc/portage/make.conf

Changing -O2 to -Os will decrease executables size a bit.

Another thing you need to worry is to build correct kernel.

If the build process is failing or slow on your device, you can try building everything in a virtual machine on a modern pc, then transfer image to the device.

To know what CPU you do have, find any bootable 'live' linux distribution (that is able to boot on your old pc, this for example http://tinycorelinux.net/) and then type cat /proc/cpuinfo. You can try to use this tiny linux as a chroot base system for your gentoo, as well.