Microcode, which is a no-go for modern designs

[Grant Taylor]

On 1/6/19 11:59 AM, Jeffrey S. Worley via cctalk wrote:
> I was a tech in the 90's when the original Pentium FDIV bug was storming. 
> The issue was confined to the integrated floating point portion of the 
> processor and was therefore rarely an issue as the vast majority of 
> software did not use the mathco portion of the chip.  Only a handful of 
> applications and relative handful of users were affected.  This became 
> Intel's position on the matter and they hoped the issue would just die 
> down to those handful whom they would provide new chips.
> 
> The issue did not die down and the bad press forced the decision to 
> replace ALL pentiums affected.  Only a relative few were actually replaced 
> in the home and small business arena.  A software patch was a common 
> solution to the problem.  It masssaged input to the FDIV instruction to 
> produce a corrected result and worked pretty well as I recall.

I suspect that Intel is longing for the Pentium FDIV bug days after the 
speculative execution issues that have surfaced (and gained traction) in 
2018.



-- 
Grant. . . .
unix || die