On what mashines is older than Pentium 4 (Socket 478 - Prescott, if I am not mistaken) can run the SMP-kernel?

The SMP kernel in its -current form can run on any CPU that does support PAE. So anything newer then Pentium Pro (except the Banias Pentium Ms) and Athlon can run that kernel. That this kernel supports SMP does not mean that it need multi-core, multi-CPU or Hyperthreading machine.

Then, the more it makes sense to abandon the non-SMP kernel. I think, a very old machines are not so much to worry about compatibility with them.

I personally think that Slackware should not drop support for the Pentium Ms and the K6-II(I) CPUs (and may be some of the VIA CPUs, I can't find information about the status of PAE on those chips). Slackware is well known for running without problems on older hardware, and many people still use those machines, especially in countries were newer hardware is expensive and money is in short supply. Dropping the non-SMP kernel would basically mean dropping recent Slackware for those people.

Of course a simple work-around for this situation would be to not enable PAE by default in the SMP kernel and then drop the non-SMP one. A user that needs PAE can easily compile a kernel with PAE enabled. That is simply not possible the other way around.

Or am I missing something? Question: Why is PAE enabled in the newer SMP kernels?

The main problem is, that a PAE capable kernel can't boot on a Non-PAE machine and a Non-PAE kernel can't use more than 4 gigabytes of memory.

Actually that's a design flaw in the Linux kernel and must be fixed upstream. PAE should be detected at runtime and activated if available.

While the first of those is a problem, the second is merely an inconvenience. I'm with Tobi' smp-enabled/pae-disabled default kernel looks to be the best option to get everyone up and running. Those who need PAE can enable it themselves post-install.

Perhaps this is part of the "Your mileage may vary" claim. I had tried and tried to install NVIDIA, but NOUVEAU was always being loaded with the huge, preventing the proprietary from being installed. Blacklisting seemed to never work for me. Then I tried the generic, and low and behold the blacklisting worked. Perhaps I was missing something - but this was how I got it to work for my machines.

On a very old machines, such as Pentium-Pro based, PAE is not needed for works. Also, find the parts for these machines every day is all more is difficult.

that's true i just installed slack on a friends machine since it is the only kernel without pae that could be used.

Too much overhead :o

i personally not use hardware running on slack, who not be minima of i686
on other hand - i see, there is be folks, who used old i586 hardware with current slack.
i think, then we can see, what bonus we have if going to i686 smp only - there is huge gap in performance? or in what? if we have a significant leap from going to i686 kernel, when we have consider that. if no - i cannot see, why not sit on an old tradition...?

As a reminder the question is asked by Pat in a file called BROKEN.TXT in /extra. This doesn't say why but I would tend to guess what he had in mind: less maintenance work and/or less payload for the ISO's and/or the installer, possibly making room for other stuff (only a guess, of course). Meanwhile, I also saw this post which you could interpret as "we will keep non-SMP" -- or not as this is not explicitly stated.

Anyway it amazes what how Pat's "offhand comments" (in his own words) can (certainly unwillingly) spread FUD in our very sensitive community. Or trigger what we call here "une tempête dans un verre d'eau" :)

As a side note I find sometimes difficult to really understand if reactions from us are expected or not, probably because English is not my native language.

It's about the pain, isn't it--compatibility. I was going to say that, if other-than-very-painful, please retain non-smp compatibility if-only for memory reasons.

Up until a month ago, I had Actual i486 & Ppro industrial pc's running it. Purely for space reasons, threw it all out (after a protracted moment of silence and some mental rhapsodizing about damned kids not appreciating kilobytes) and replaced it all with wall-wart-driven "gadgets".

It's not just another lame Geezer-nostalgia rant, more a commentary on a lost decade of an economy. The industrial stuff...well few have had anything to spend on capital equipment for a Good While (tm).

Arguably a narrow use-case, but I'd bet it's larger than people think. New software doesn't support old hardware. Old hardware comes as part of 6- and 7-figure machinery and equipment. Retrofitting/upgrades are within 25% of all-new hardware (aka prohibitive to financial people seeking ever-faster paybacks).

Okay, it turns-out this was a Geezer-rant. It's just a reaction from having been through this pinch a few times before in other forms. Heavy machines and equipment last for decades. Talking to them is ever-more-difficult, but that's not Pat's problem and it's not any of the Slackware Team's problem. I have nothing but gratitude for them.

If i486 survives another rev--great! After that, call it a nice-to-have and let the world move-on (but light a candle first and scream "Gawd save the Queen!", will you?)

Please explain.