Re: FW: I think I've found a serious bug in AMD Athlon page_alloc.c

Mark Hahn (hahn@coffee.psychology.mcmaster.ca)
Tue, 15 May 2001 19:01:24 -0400 (EDT)


> I think I've found a serious bug in AMD Athlon page_alloc.c routines in

there's nothing athlon-specific there.

> correct on the DFI AK75-EC motherboard, if I set the CPU kernel type to 586
> everything is 100%, if I use "Athlon" kernel type I get:
> kernel BUG at page_alloc.c:73

when you select athlon at compile time, you're mainly
getting Arjan's athlon-specific page-clear and -copy functions
(along with some relatively trivial alignment changes).
these functions are ~3x as fast as the generic ones,
and seem to cause dram/cpu-related oopes on some machines.

in short: faster code pushes the hardware past stability.
there's no reason, so far, to think that there's anything
wrong with the code - Alan had a possible issue with prefetching
and very old Atlons, but the people reporting problems like this
are actually running kt133a and new fsb133 Athlons.

> I've changed RAM, Motherboard etc... still the same.

changed to a non-kt133a board? how about running fsb and/or dram
at 100, rather than 133?

> Also the same system runs linux-2.2.16 100%

2.2 doesn't have the fast page-clear and -copy code afaik.

afaik, there are *no* problems on kt133 machines,
and haven't heard any pain from people who might have
Ali Magic1, AMD 760 or KT266 boards, but they're still rare.

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