Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

H. Peter Anvin
2007-12-11T05:54:19Z

Andi Kleen wrote:
>> My machine in question, for example, needs no waiting within CMOS_READs
>> at all. And I doubt any other chip/device needs waiting that isn't
>
> I don't know about CMOS, but there were definitely some not too ancient
> systems (let's say not more than 10 years) who required IO delays in the
> floppy driver and the 8253/8259. But on those the jumps are already
> far too fast.
>

Yes, early Linux used jumps. I believe it broke a bunch of machines
when the P5 came out, as the jumps were too fast. (I have to admit to
being a bit fuzzy on this... my memory says it was the 486 and not the
P5, but that clearly can't be the case since my first Linux box was a
486/33.)

-hpa