how to tell 64 vs 32 bit architecture ?

[M. Warner Losh]

In message: <20070906111028.A83649 at xorpc.icir.org>
            Luigi Rizzo <rizzo at icir.org> writes:
: hi,
: i was wondering what is the proper way to tell a 64 vs 32 bit architecture.
: 
: I see that some code in sys/ uses  ' #ifdef __LP64__ ' but i am not
: sure if this is generic enough (ie not gcc or FreeBSD specific),
: and also suitable for userland (i.e. works on linux or other platforms
: as well).

It is portable.  gcc, and other compilers, define this when using
longs and pointers as 64 bit.  There's also ILP32 and ILP64
programming models, but only windows 64 uses the latter.

Typically, however, there are better ways to solve problems relating
to these differences.  What kinds of problems are you trying to solve?

Warner