# strace modprobe bcm43xx 2>&1 | grep modprobe.d
open("/etc/modprobe.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 3
open("/etc/modprobe.d/modprobe.conf", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = -1 ENOTDIR (Not a directory)
open("/etc/modprobe.d/modprobe.conf", O_RDONLY) = 4
open("/etc/modprobe.d/isapnp", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = -1 ENOTDIR (Not a directory)
open("/etc/modprobe.d/isapnp", O_RDONLY) = 4
open("/etc/modprobe.d/blacklist", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = -1 ENOTDIR (Not a directory)
open("/etc/modprobe.d/blacklist", O_RDONLY) = 4
open("/etc/modprobe.d", O_RDONLY)       = 3

# ls -l /etc/modprobe.d
total 12
-rw-r--r-- 1 root root 6354 2007-05-26 23:34 blacklist
-rw-r--r-- 1 root root  330 2007-05-26 23:33 isapnp
lrwxrwxrwx 1 root root   16 2007-03-28 09:12 modprobe.conf -> ../modprobe.conf