2.0.3[345]/SMP/Boomerang - big IRQ reentry problems :-(

Frederick F. Gleason fredg@wava.com
Wed Jul 22 15:57:10 1998

On Wed, 22 Jul 1998, Adam Spiers wrote:

> After pounding on our dual-400MHz Pentium-II system for the last 48
> hours without a crash, it looks as though this "Re-entering interrupt
> handler" problem has been cured by applying to our 2.0.34 kernel the
> "mtrr-fix" patch. Prior to applying the mtrr-fix, the dual-CPU system
> wasn't staying up longer than 24 hours without wedging itself with the
> "Re-entering interrupt handler" problem.
> The "mtrr-fix" compensates for broken SMP BIOSes which do not
> synchronize MTRRs (memory type range registers) across all
> CPUs. Mathias Froehlich has written a patch for 2.0.3x which has a
> similar BIOS fix; it is available from this URL:
> http://na.uni-tuebingen.de/~frohlich/mtrr-stuff/mtrr-fix-2.0.33.gz
> Since this patch has apparently worked for us, it appears that the
> ASUS P2B-DS motherboard's BIOS has the cache synchronization problem.

It appears that this is indeed a BIOS issue -- I've got a dual PPro 200
system with a 3C905-TX that's been in service for six months, running
SMP kernels 2.0.30 through 2.0.35, and I've never seen this problem.

My $.02

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