Re: x86S Specification

John Levine <johnl@taugh.com> writes:

Think about the way that current Intel chips have a native 64 bit architecture
but can still have a 32 bit user mode that can run existing 32 bit application
binaries. So how about if the next generation is native x86S, but can also run
existing 64 bit binaries, even if not as fast as native x86S. They get the usual
cloud operating systems ported to x86S while leaving a path for people to migrate
their existing applications gradually.

Several things in this paragraph makes no sense.

In particular, x86S is a proposal for a reduced version of the stuff
that current Intel and AMD CPUs support: There is full 64-bit support,
and 32-bit user-level support.  x86S eliminates a part of the
compatibility path from systems of yesteryear, but not that many
people use these parts nowadays anyway.  It's unclear to me what
benefits these changes are supposed to buy (unlike the elimination of
A32/T32 from some ARM chips, which obviously eliminates the whole
A32/T32 decoding path).  It seems to me that most of the complexity of
current CPUs would still be there.

And I certainly prefer a CPU that has more capabilities to one that
has less capabilities.  Sometimes I want to run old binaries.

So what would be my incentive as a user to buy an x86S CPU?  Will they
sell them for less?  I doubt it.

- anton
--
'Anyone trying for "industrial quality" ISA should avoid undefined behavior.'
  Mitch Alsup, <c17fcd89-f024-40e7-a594-88a85ac10d20o@googlegroups.com>