Poke's post sounds like a troll, but what the heck, I'll respond.
At 08:43 PM 1999/09/21 -0700, poke wrote:
>
>All programs are affected by the FDIV bug.
No. Not all programs use the FPU. Some that do, do not use instructions
affected by the bug.
>It is a bug in the design of
>the microprocessor.
Yes. But there was a recall program of about a year's duration, back
when the P5-100 was the fastest rated speed that Intel sold.
>Linus has a way around it.
>The brain dead morons at Microsoft have to make everyone else wait
>for a solution
>(That has yet to come AFIK).
Microsoft announced patches years ago, for FDIV error workarounds
in their operating systems of the time, as well as the calculator applet
and the Excel spreadsheet.
>Linux on the other hand usually has problems solved in a
>matter of hours.
Microsoft does regression testing of patches before releasing.
They don't always get it right on the first release of their patches,
but the variety of combinations that face them is mind-numbing.
It's hard to imagine that a thorough regression testing could be
performed in a few hours.
This is not meant to be flamebait; just stating the facts as I recall
them. I know and respect coworkers who regularly use Linux, and
occasionally use it myself.
>-Chuck
>
>
>
>On Tue, 21 Sep 1999, Floris Looyesteyn wrote:
>
>> I was wondering if Prime95 is affected by the Pentium
>> FDIV bug. (or some name like that).
My recollection is Prime95 is unaffected. Will Edgington had not at that
time detected any factors missed due to the pentium FDIV bug.
George and I had a conversation about workarounds for the pentium FDIV bug
3 June 1996. Here are some old URL's I included then.
See http://pentium.intel.com/procs/support/pentium/fdiv/swpatch/patch.txt
This includes the personal names of the discoveror and other early
investigators.
See also a couple levels up from that page for more info.
Also:
http://www.free.net/ftp/systems/pentium/division.letter
for someone else's approach to the calculate both ways and check method.
http://almond.srv.cs.cmu.edu/afs/cs.cmu.edu/project/verify/www/srt-bdd.html
search April issues of Dr Dobb's journal for an article by Time Coe.
http://enigma.db.erau.edu/~flynnt/pentium.html for a FAQ. Also has Nicely
matl.
Nicely discovered the flaw.
http://www.mathworks.com/README.html "The Pentium Papers", many links.
coe.txt and pratt.txt are worth reading.
also moler_6 and moler_7.
http://www.mathworks.com/Moler_7.txt
If you detect a buggy pentium, you must shift your operands out of the
situation where the known-bad bit pattern occurs in one of the divide
attempts.
The gist of it is, scale operands by 3 to ensure differing bit patterns, and
there's a sizable performance hit.
>> I ask this because now i'm also using it on my laptop
>> (great work george!) and when i installed linux some time
>> ago it said the processor had this bug.
>>
>> Floris Looyesteyn
Ken
Ken Kriesel, PE <[EMAIL PROTECTED]>
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