What I know about this subject is that Intel puts some undocumented
operations into its processors. Those are instructions that are accesible
from a software that is using the processor, but should be used internally
in Intel only and Intel does not guarantee to support them in later
processors of the same architecture.
For instance, the Pentium (vanillaor MMX) line of computers used to have a
way to retrieve a 64-bit integers which had the number of clock iterations
that have passed since the computer had been turned on. When I worked in
Smart-Link they used it to determine the Frequency of the computer.
However, it wasn't supported in AMD or in Pentium Pro's or Pentium II's.
I once saw a web-site that aimed at documenting the "undocumented"
instructions of the Pentium family of computers, but I don't remember its
URL. (STFE ?) Naturally, it was a hackers site and not an official Intel
one.
I wonder if such a pragma is possible in RISC architectures, because they
generall have much less available instructions than SISCish architectures
such as the i386's.
In any case, I don't think the Linux kernel, glics or much less any
application that is written in pure C, relies on any of those games, so it
should be safe to assume that they will be forward-compatible with the
Pentium 4.
Regards,
Shlomi Fish
----------------------------------------------------------------------
Shlomi Fish [EMAIL PROTECTED]
Home Page: http://t2.technion.ac.il/~shlomif/
Home E-mail: [EMAIL PROTECTED]
A more experienced programmer does not make less bugs. He just realizes
what went wrong more quickly.
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