Re: Errata 67/77 / walnut bugs (was: Re: Erratum 51 bugfix?)

David Gibson wrote:

Ah, yes, I discovered ATOMIC_SYNC_FIX after I sent that, and have now
turned it on.  That should certainly fix the atomic ops, however there
are quite a number of other places where the kernel uses stwcx., which
ATOMIX_SYNC_FIX doesn't fix - notably arch/ppc/kernel/bitops.c and
include/asm-ppc/bitops.h.  As well as activating ATOMIX_SYNC_FIX I
tried inserting a sync before every other stwcx. that I could find,
and I haven't managed to get a process to lock up yet.

Just as an FYI, we also do this in glibc to be safe.  We have never been
able to pin down a problem in userspace due to this bug, but we thought
it would be better safe then sorry until we can get definative proof
that the bug will not happen in userspace.

The following two files in glibc should be patched:
linuxthreads/sysdeps/powerpc/pt-machine.h
sysdeps/powerpc/atomicity.h

--Mark

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