Edit the Makefile in the asterisk installation folder.
scroll down to this area:
ASTCFLAGS=
# Pentium Pro Optimize
#PROC=i686
# Pentium & VIA processors optimize
PROC=i586
#PROC=k6
#PROC=ppc
Uncomment the “PROC=i586″ line before compiling and all will be well. Otherwise after compilation, you will get an error message simply stating “Illegal instruction” when trying to run asterisk.
