The kld interface allows system administrators to dynamically add and remove functionality from a running system. This allows device driver writers to load their new changes into a running kernel without constantly rebooting to test changes.
The kld interface is used through:
kldload
- loads a new kernel
modulekldunload
- unloads a kernel
modulekldstat
- lists loaded
modulesSkeleton Layout of a kernel module
/* * KLD Skeleton * Inspired by Andrew Reiter's Daemonnews article */ #include <sys/types.h> #include <sys/module.h> #include <sys/systm.h> /* uprintf */ #include <sys/errno.h> #include <sys/param.h> /* defines used in kernel.h */ #include <sys/kernel.h> /* types used in module initialization */ /* * Load handler that deals with the loading and unloading of a KLD. */ static int skel_loader(struct module *m, int what, void *arg) { int err = 0; switch (what) { case MOD_LOAD: /* kldload */ uprintf("Skeleton KLD loaded.\n"); break; case MOD_UNLOAD: uprintf("Skeleton KLD unloaded.\n"); break; default: err = EOPNOTSUPP; break; } return(err); } /* Declare this module to the rest of the kernel */ static moduledata_t skel_mod = { "skel", skel_loader, NULL }; DECLARE_MODULE(skeleton, skel_mod, SI_SUB_KLD, SI_ORDER_ANY);
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