发信人: Creative()
整理人: pcsoul(2001-01-18 17:03:52), 站内信件
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以下是一段文字,声称 Pentium Pro & II 在浮点方面有 bug ?!
文章摘自 www.news.com :
An engineer dedicated to tracking inside
information about Intel processors reported today
that Intel's Pentium Pro and its upcoming Pentium II
processors have a bug that could result in a PC
producing bad data.
Robert Collins, the publisher of the Intel Secrets
Web site, this morning released a detailed
explanation of what he is calling a bug, as well as
software to test the Pentium Pro and Pentium II for
the bug.
Intel is conceding today that the Collins report
identifies a "real issue."
"When you see things that are this technically
explored they tend to have validity," said Howard
High, an Intel spokesperson.
However, the seriousness of the bug is far from
clear at this point. Some students at the
Massachusetts Institute of Technology (MIT) who
looked at Collins' report claim that it is "extremely
minor."
Both Intel and Collins are being extremely cagey
about characterizing the nature of the problem.
Collins, a fomer Texas Instruments engineer, says
that he does not know if it could have any real
impact for a typical PC user. "I don't know the
answer to that," he said.
He added, however, that bugs are often reported
by Intel as erratum and made public and that this is
not really any different than past bugs which are
typically not reported in the press.
Collins says the bug is related to operations where
the chip converts floating point numbers into integer
numbers. Floating point operations are typically
used in scientific and engineering software
programs.
Collins' report explains that floating point and
integer numbers are stored in different formats
inside a processor. The chip may choose to convert
a floating point number into an integer number but if
it doesn't fit in the smaller integer format, an error
can occur.
If that happens, the processor is supposed to warn
the computer's software as mandated by IEEE
Floating Point Standards. The problem here,
according to Collins, is that the chip is not setting up
a warning flag when the error occurs.
In an attempt to describe the nature of the bug,
Collins compared it to a widely reported error that
occured during an Arian 5 rocket launch. In that
case, less than a minute into the launch, a computer
on board suffered from a similar floating point
irregularity that prompted it to dump its memory.
"Unfortunately, this memory dump was interpreted
by the rocket as instructions to its rocket nozzles.
Result--boom!" Collins said.
But some observers at MIT claim this example is
somewhat sensational and is not related to the
problem.
The bug is also reminiscent of, but not the same as,
the infamous floating point bug in the original
Pentium chip. That bug, reported two years ago,
resulted in very rare instances in inaccurate
computations and sparked an angry backlash from
users against Intel for its handling of the problem.
High said Intel engineers are now studying the
Collins posting and will "fully characterize" the
problem by the end of the week. If there indeed is a
bug, Intel will label it as a Pentium Pro "erratum."
"It appears that the processor is not operating
within the processor specification [because of the
purported bug]," High said. Intel calls anything that
does not operate within the specification an
erratum.
Collins says he found the bug while using his own
testing software on Pentium Pro and Pentium II
processors after an anonoymous discoverer tipped
him off to the problem. Collins has dubbed the bug
"Dan-0411" after its original discoverer and the
date he received the tip, April 11.
Collins also tested Intel 486, Pentium, Pentium with
MMX, and AMD K6 processors but didn't find the
bug in any of these other chips.
Intel is an investor in CNET: The Computer
Network.
Creative
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