>> It is only *atomic* accesses (those implemented using the S/390
>> compare-and-swap instruction) that need to be word aligned; this
>> the atomic bit operations that reiserfs appears to be using.
>Aren't their some other "must align" instructions like CVB? Or have they
>all been relaxed...
CVB doesn't have any alignment requirement (I'm not sure it ever had one).
Execpt for the 'atomic' operations (CS, CSG, CDS, CDSG, LPQ, STPQ, PLO)
I know only of two general-purpose instructions with operand alignment
requirement, and that's LAM and STAM. As access registers are not
normally used in Linux this shouldn't be a problem.
There *is* a whole bunch of privileged system instructions that have
various aligment requirements; but here I'd say it's fair to require the
user to provide correct aligment in these special cases.
Mit freundlichen Gruessen / Best Regards
-- Dr. Ulrich Weigand Linux for S/390 Design & Development IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen Phone: +49-7031/16-3727 --- Email: Ulrich.Weigand@de.ibm.com
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