RELEASE BLOCKER: Linux doesn't follow x86/x86-64 ABI wrt direction flag

[H. Peter Anvin]

Robert Dewar wrote:
> 
> Sounds good, but has almost nothing to do with the real world. I 
> remember back in Realia COBOL days, we had to carefully copy IBM
> bugs in the IBM mainframe COBOL compiler. Doing things right and
> fixing the bug would have been the right thing to do, but no one
> would have used Realia COBOL :-)
> 
> Another story, the sad story of the intel chip (I think it was
> the 80188) where Intel made use of Int 5, which was documented
> as reserved. Unfortunately, Microsoft/IBM had used this for
> print screen or some such. Intel was absolutely right that
> their documentation was clear and it was wrong to have used
> these interrupts .. but the result was a warehouse of unused
> chips.

IBM used it for print screen (and other calls), because Microsoft 
cassette BASIC used all the non-reserved INT instructions as byte codes 
(they cut it down to *only* half the interrupt vectors in the disk version.)

We're still stuck with the consequences of that hack.

	-hpa