Migrating 5.2 from Pentium 4 to Athlon MP

[Ihsan Junaidi]

Hello all,

I have a server currently running on a Pentium 4 box. Yesterday I bought 
an AMD 762 MPX chipset to go with two Athlon MP 2000+. The production 
server is running FreeBSD 5.2, a GENERIC with additional SCSI/RAID 
controllers trimmed off.

The kernel and all of the userland + ports were built with -march=p4 
flags and I am wondering if there's any way I can just plug the disk 
into the Athlon box without rebuilding everything with the exception of 
the world+kernel. FYI, the kernel is SMP-aware.

How does the -march flag effect the userland programs? I am aware that 
only OpenSSL is capable of taking advantage of specific CPU instructions 
but other than that?

Thank you for your time,
Ihsan