Hi, I'm considering building a system based on an AMD Athlon 64 and a
flavour of 64-bit Linux (e.g. RedHat Fedora Core 3).

I was under the impression that these new 64-bit CPU's have
a feature similar to the old notion of separate I and D spaces,
i.e. you can map memory to be data-only, and it won't ever execute.

However, reading between the lines, I see there are some
security updates on some 64-bit linuxes that imply that this
feature isn't used, in particular "buffer overruns" causing
potential "remote code execution".

I have been unable to find out from the various Linux vendors
whether their 64-bit implementation is safe from this respect,
does anyone know the score here? Am I either mistaken about the
capabilities of the x86_64 architecture, or has no-one bothered
to fully exploit them yet?

Thanks and have a good 'X'mas

- Adam