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386-DX/SX support nuked from Linux Kernel

git.kernel.org

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Re: 386-DX/SX support nuked from Linux Kernel

#81

Post by dalke »

huxley wrote: post #79
dalke wrote: post #63

Earlier quoted context omitted.

640KB was the max RAM. My first PC was the same configuration, except I had a 32MB drive. Oh! And towards the end I had both a CGA and Hercules card so I could have two screens.

PCs released after the XT could be configured with up to 640KB but the original IBM PC was limited to a max of 256KB (entry level config was 64KB).

It looks like the model 5150 didn't come with a hard disk, and the only official support for that was through the IBM 5161 Expansion Chassis. I think the author would have commented having an external drive for a PC, so I think it's safe to assume at least an XT equivalent.

(I've been searching for images of the chassis but to no success. I've never seen one, nor heard of it before today.)

And in the other direction, a PC Jr (also an 8088) maxed out at 128 KB, according to my references, though Wikipedia says there were third-party extensions to 736K. In any case, the Jr doesn't support the 8087 math coprocessor, so that's not what the author has.

Re: 386-DX/SX support nuked from Linux Kernel

#82

Post by dalke »

yuhong wrote: post #80
huxley wrote: post #79

Earlier quoted context omitted.

PCs released after the XT could be configured with up to 640KB but the original IBM PC was limited to a max of 256KB (entry level config was 64KB).

On the motherboard. You could still add RAM using ISA cards.

To confirm, http://www.pcworld.com/article/237878/can_you_do_real_work_w... shows a model 5150 (it's the only model with a cassette port on the back) which has 640K of RAM.

Re: 386-DX/SX support nuked from Linux Kernel

#83

Post by Turing_Machine »

j45 wrote: post #12

386's were the first computers I ever used Linux on. Man. I will say this much, a 386 sx/16 was a large part of learning learn how to get so much done with so little resources. It's amazing how Linux was more efficient than windows even then, while the decade of driver drought was being bridged.

Yep, same here, 386 SX/16 FTW, installed from floppy images created with rawrite.

"Distro"? What's that? :-)

That said, it's time. Long past.

Re: 386-DX/SX support nuked from Linux Kernel

#84

Post by marris »

Does anyone know what the speculative execution notes in processor.h are talking about? The code seems to be trying to set up spec execution "barriers."

What does that mean? I thought speculative execution was a micro-architecture optimization (and the speculatively executed instructions won't be retired until the processor knows that it wants the side-effects).

In contrast, I've only seen barriers come up for x86 at the ISA-level (and even then, only for multiprocessors setups).

Re: 386-DX/SX support nuked from Linux Kernel

#85

Post by amorphid »

dalke wrote: post #81
huxley wrote: post #79

Earlier quoted context omitted.

PCs released after the XT could be configured with up to 640KB but the original IBM PC was limited to a max of 256KB (entry level config was 64KB).

It looks like the model 5150 didn't come with a hard disk, and the only official support for that was through the IBM 5161 Expansion Chassis. I think the author would have commented having an external drive for a PC, so I think it's safe to assume at least an XT equivalent. (I've been searching for images of the chassis but to no success. I've never seen one, nor heard of it before today.) And in the other direction,…

I had a PC jr. The base model, which I had, came with 128k of memory, a single 5.25" inch floppy, and 2 cartridge slots. I booted DOS via a cartridge. There was an expansion unit you could purchase which had a 2nd floppy (very handy!) and I think it expanded max memory to 640k (but might have only been 256k).

Re: 386-DX/SX support nuked from Linux Kernel

#86

Post by robin_reala »

ynniv wrote: post #75
robin_reala wrote: post #39

Earlier quoted context omitted.

RISC OS is still going (they just released a Raspberry Pi build) and OS/2 morphed into the commercial eComStation that is actively maintained. NeXT is dead though and Amiga fractured.

NeXT is dead Didn't you get the memo?

OK, fair point :)

Re: 386-DX/SX support nuked from Linux Kernel

#87

Post by primitur »

stusmall wrote: post #73
primitur wrote: post #33

Earlier quoted context omitted.

Linux is used in a lot of places these days, where VxWorks or QNX might've been. I've been responsible for putting Linux to work in SIL-4 critical systems all over Europe, for example, saving millions in licensing costs while at the same time, getting Linux certified for safety-critical apps. It really is taking over.

Whats the current state of the real-time patches for linux? Last I'd talk to someone about them, this was a while ago, they felt a bit sub-par. From a developer's point of view is it as easy to work with and predictable as VxWorks?

Sure, its easy to work with. Just don't always try to work with the latest, bleeding edge kernels. Most RT/Safety-Critical Linux kernel installs are still based on 2.6.x, or even some cases, 2.4.x series ..

Re: 386-DX/SX support nuked from Linux Kernel

#88

Post by jmspring »

sageikosa wrote: post #67
maximilianburke wrote: post #60

Earlier quoted context omitted.

All 386's lacked the math co-processor, the SX just had a 16-bit data bus.

Yep. The 486SX was the 486 with disconnected math processors that failed quality control. The coprocessor "487" upgrade chip was simply a fully working pin incompatible (only fit in the upgrade slot) 486. On the 386 line, the SX/DX distinction was the equivalent of the 8088/8086 distinction for data bus width (NOTE: the 8086 was the wider processor, the cheaper 8088 was in the IBM PC).

Yeah, I meant the 486sx, but the little grey cells were not up to snuff when posting that apparently.

I got a fair amount of grief about not having a math co-processor due to some programming friends and I were doing at the time.

That said, those were the formative days where getting dirty and playing with your machine (building your own rig) started for me. I've since given that up since most machines are fast enough these days for my uses.

Re: 386-DX/SX support nuked from Linux Kernel

#89

Post by Natsu »

dalke wrote: post #81
huxley wrote: post #79

Earlier quoted context omitted.

PCs released after the XT could be configured with up to 640KB but the original IBM PC was limited to a max of 256KB (entry level config was 64KB).

It looks like the model 5150 didn't come with a hard disk, and the only official support for that was through the IBM 5161 Expansion Chassis. I think the author would have commented having an external drive for a PC, so I think it's safe to assume at least an XT equivalent. (I've been searching for images of the chassis but to no success. I've never seen one, nor heard of it before today.) And in the other direction,…

It says it's a 5160 on the back by the power supply. The HD is, in fact, internal. And there's a phone jack on a card in back that looks newer than the rest, so it might have some kind of modem, though I have no idea how fast that is.

I also have no idea if it still works. It was covered in quite a bit of dust and I wonder if the HD won't be stuck after all this time.

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