What's going on here?

$ mount
/dev/wd0a on / type ffs (local)
/dev/wd0e on /usr type ffs (local)
/dev/wd0f on /usr/pkgsrc type lfs (local)
$ cd /usr/pkgsrc
$ echo "main(){return(0);}" >test.c
$ gcc -o test test.c
$ ./test
Memory fault (core dumped) 
$ cp /bin/sh .
$ ./sh
Memory fault 

:: Mike ::