core2 duo cpu optimizations in fedora kernels?

[Gianluca Cecchi]

hello,
I would like to post a generic question and a specific one.

1) I noticed that in EL kernels and also in fedora ones, the cpu
optimization selection in .config is generic CONFIG_M686 (that should
be PPro if I'm not wrong). Instead, in huge kernels there is
CONFIG_MPENTIUMIII set, I think because it was the first with PAE
capability perhaps?
Would one benefit getting the kernel.src.rpm package and compiling
with set up based on his own traget processor? For example
CONFIG_MPENTIUM4?
I think after PPro many microarchitecture changes has come...
Any drawbacks or possible incompatibility with the rest of the system?

2) If the answer to 1) it's worth while, what kind of optimizations
could I get for Core2 duo processor based systems, or in the future
for woodcrest?
It seems to me that, simply said, core2 duo takes the best from PIII
and PXeon features, so if you select one of the two you however
probably miss something....
Does the gcc version provided with fedora support optimizations for
these new processors? And in case are these mapped in kernel
capabilities then?
Does it make sense to consider intel compiler to compile kernel, as
for example it supports on Linux the switches -xT or –axT for
Merom/Conroe/Woodcrest processors?

Otherwise how could we get all the features provided by these new cpus?

thanks in advance.
Gianluca