Messages in this thread | | | Date | Mon, 10 Nov 1997 14:17:53 +0100 | From | Andre Derrick Balsa <> | Subject | Re: Pentium DEATH and Cyrix COMA in user-mode |
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Hi Alan,
Alan Cox wrote:
> They are very similar it appears. One is "lock cmpxchg8" which causes a double > lock cycle on the bus (I believe its to the bus), the other is a dual issue > of an implicitly locked operation (again dual lock). >
Yes, it is the CPU bus that gets locked i.e. interrupts are not serviced and other bus masters are not granted access to the CPU bus.
Cyrix 6x86 CPUs have a NO_LOCK flag in a control register that disables the implicit locking of xchg instructions (among other things).
This effectively prevents the Cyrix bug. I am still testing to check if it has other negative effects.
On my two 6x86 Linux boxes it seems to be an acceptable solution.
If a similar solution could be found for the Pentium F0 bug, it could save Intel a few billion dollars...
Cheers,
======================================================== Andrew D. Balsa Home Page: http://www.tux.org/~balsa andrewbalsa@usa.net ========================================================
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