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Re: pentium bug

See inline comments.

| From: (root)
| Subject: pentium bug
| To:
| Date: Sat, 8 Nov 1997 17:19:42 +0100 (MET)
| Then, I ported the code to my old faithful 486-DX33 with linux. Compiled it.
| When it run it traps with 'illegal instruction'

Not surprising.  This is a "lock cmpxchg8b eax" instruction, which is new
to the Pentium series and also nonsensical.

| This means that anybody can crash anytime any OS that runs under a Pentium.
| This means that no secure system can ever be built that uses the pentium CPU. No
| protected system. The OS receives NO TRAP!!!

Yup, this is *very* bad news for all those ISPs out there on pentiums.

| Bugs are impossible to avoid. Not even with huge corporations like Intel.
| I will *not* start screaming at Intel now. Myself, I have done more bugs
| than Intel ever will. As somene said before:
| Those that are free of sin, throw the first stone...

Well, personally, I'd fire the engineer responsible for that instruction.
Illegal instruction trap tests are fairly basic and whomever designed that
instruction should have insisted and ensured that the illegal sequences
were properly included in the regression tests.

Bugs that folks can work around are forgivable.  Bugs that require the
wholesale recall of an entire product line?  Uh, this is a little more
than just an "oops, sorry."

Hmmm, wholesale recall is probably a bit harsh -- if you're not trying to
run a secure site (eg.  you're just using the pentium for a single-user
workstation), then there really isn't too much to worry about.

Hehe.  My secure system is still on a 486, simply 'cuz a 486/66 with
FreeBSD beats a P5/200 running Windows 95.  I'll need to demand a fix when
it comes time to upgrade to the next MS OS, which no doubt will run even
slower and thus need a faster processor, but at least I have some time to
wait for Intel to get a replacement program in place.  I suspect 90% of
pentium users can also afford to wait.

- Tim Iverson
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