Re: JavaMemoryModel: A couple of things...

From: David Holmes (
Date: Sun Nov 21 1999 - 17:02:45 EST

> On what machines are the standard instructions for partial word
> updates guaranteed to by atomic?

This issue of "word-tearing" was first raised (that I know of) around April
98. By a fairly reasonable interpretation of the spec word-tearing is not
permitted - but Guy Steele agreed that the spec should be more explicit.

As for machines ...

The Alpha architectures allow the atomicity of accesses to partial words to
be configurable ie. it doesn't have to be atomic. Perhaps one of the Compaq
(nee Digital) folk can tell us about specific implementations.

IA-64 doesn't seem to mention this explicitly - so what can we infer from

PA-RISC guarantees atomicity (except some I/O related stores).

Don't have a SPARC Architecture manual :-(


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