RE: [Linux-ia64] New rev 2.1 SDM for Itanium published

Jim Hull
2002-11-22T18:08:39Z

Matt wrote:

> On Thu, Nov 21, 2002 at 07:47:11AM -0800, Mallick, Asit K wrote:
> > This version includes the 3 new instructions:
> > - atomic ops (16 byte compare and exchange)
>
> I presume this one is not backwards-compatible with existing processor
> implementations?

Correct.

> If so, should this be noted somewhere so that naive
> people who read the manuals don't assume that it's implemented?

There is a new "ao" bit in CPUID[4], which as described on p. 1:32, will
be 1 only if the new larger atomic ops are implemented. Do you think
this is insufficient?

-- Jim
HP IPF Processor Architect