Re: f00f

Richard B. Johnson (root@chaos.analogic.com)
Mon, 17 Aug 1998 10:09:26 -0400 (EDT)


On Tue, 18 Aug 1998, root wrote:

> what is the f00f bug on intel chips
> David <sector2@ihug.co.nz>

0xF0 0x0F is the preamble to a locked instruction, hense the name.
Certain locked instructions, which should have produced an illegal
opcode trap, didn't. This could cause the processor to shut down
from such user-mode instructions. The fix was to cause a page-fault
on this instruction sequence so the processor could get control
in the page-fault handler, rather than shut down. This processor
bug-fix is very nice because it normally has no overhead at all.

Cheers,
Dick Johnson
***** FILE SYSTEM WAS MODIFIED *****
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