FPU on a future builds ?

[Badwolf]

As Stephen Usher says, the Mint's GCC build only really has two build chains supported: 68000 and 020-060. The latter assumes FPU and is the subject of much debate (as @mikro can attest, I'm sure! https://github.com/freemint/m68k-atari- ... c/issues/1).

To that end lots and lots of sofware 'seems' to need an FPU (even if it doesn't) and, unfortunately, I don't think Anders' FPU emulator is presently context-switching safe (so whilst it works well in MonoTOS, once you get MiNT involved it kind of gets dicey. And of course MiNT is really where you want it because of the above).

The alternative is to NOT instally any apparently '030 optimised' software, and instead use the 68000 version. Good luck explaining that to users.

It's why I added an FPU to DFB1. I probably wouldn't have if we had a fully working softfpu.

BW

[exxos]

Couldn't the FPU register simply be faked to give the impression it has an FPU to keep mint happy ?

Of course it would only work with software which doesn't actually need a FPU, but if its only checking for its presence and that is the only thing which is breaking software....

[Steve]

Yes that can be done Chris, but Mikro said he didn't want to do that because 1. What happens when you have a machine with a real FPU (would this imply two entirely different distributions? And if you go that far, why not just compile the whole thing without FPU requirements) and 2. programs that actually do use FPU calculations would be very slow, people would potentially report / complain that their fractal is taking 4 years to render. You couldn't simply have a 'dummy' FPU, as some software does use some FPU function.

[exxos]

Anyone who has ever tried to make an 030 accelerator card will tell you that the FPU makes the timings much much worse so if you want a stable working board lots of care has to be made with the layout.

Like all the time I spent getting the FPU stable on the DFB1X you mean.. :lol:

[exxos]

1. What happens when you have a machine with a real FPU (would this imply two entirely different distributions?

I wouldn't think so ? I mean if software doesn't use the FPU, then a register hack or a real FPU wouldn't matter.

And if you go that far, why not just compile the whole thing without FPU requirements) and 2. programs that actually do use FPU calculations would be very slow, people would potentially report / complain that their fractal is taking 4 years to render. You couldn't simply have a 'dummy' FPU, as some software does use some FPU function.

The users would have to be aware of that problem. I mean its kinda a problem already as it is. Problem is, the user probably wouldn't know if it uses a FPU or not. Maybe mint checks for the FPU "some way" and on any other functions issue a bus error.. problem is , users may blame minit when they don't understand the problem. But they kinda already got that problem already as no FPU will crash anyway.

Though wouldn't mint "politely" crash on "no FPU" and inform the user anyway ? If that's the case, then it could simply inform the user of no real FPU if its accessed and no real FPU is there. The dummy FPU would not really be a issue, software works, or it doesn't, no more than it crashing out on no FPU machines anyway.

So basically:

1) Default behaviour - No FPU = crash everything (should inform user anyway)
2) Dummy FPU - "most" software will work fine, as long as no real FPU accesses.
3) Dummy FPU with real FPU access = crash. (should inform user anyway)

So I don't think having the dummy is really going to cause any more problems > its just going to make a load of stuff work whereas before it wouldn't... ?

[Steve]

You'd have to take it up with Mikro, or at least read his many many pages of explanations as to why he thinks it's a bad idea. But from what I gather it basically boiled down to: stupid users, submitting bug reports because they don't know what they have.

There's nothing stopping people from using an fpu emulator themselves. He just won't include it in the mint package as default. Then if those users have a problem, they were smart enough to put the FPU emulator there themselves, so they're probably smart enough to figure out that's their problem.