Sorry about the thread name, I can't find a proper name fot it. 
question 1: how to build the system without lib32?
from the kernel config file:
and in the installation process:
sysinstall->config->distribution->
but when make buildworld and make installworld I still get lib32, how to avoid? can we set something in make.conf to aboid it? and without lib32 is safe?
question 2:
I kown "/usr/src" is for the system(kernel and userland) source, but when I make buildworld or make buidlkernel, where the system conpile source file, is all the compilation occured in "/usr/obj"? and the compilation result is also stored in "/usr/obj"?
quetion 3 how to restore the whole system file's permission? Is there some basic guilde or rule about the system file initial permissing?

question 1: how to build the system without lib32?
from the kernel config file:
options COMPAT_IA32 # Compatible with i386 binaries
and in the installation process:
sysinstall->config->distribution->
[ ] lib32 32-bit runtime compatibility libraries
but when make buildworld and make installworld I still get lib32, how to avoid? can we set something in make.conf to aboid it? and without lib32 is safe?
question 2:
I kown "/usr/src" is for the system(kernel and userland) source, but when I make buildworld or make buidlkernel, where the system conpile source file, is all the compilation occured in "/usr/obj"? and the compilation result is also stored in "/usr/obj"?
quetion 3 how to restore the whole system file's permission? Is there some basic guilde or rule about the system file initial permissing?