NAME

       config_intrhook  —  schedule  a function to be run after interrupts have been enabled, but before root is
       mounted

SYNOPSIS

       #include <sys/kernel.h>

       int
       config_intrhook_establish(struct intr_config_hook *hook);

       void
       config_intrhook_disestablish(struct intr_config_hook *hook);

DESCRIPTION

       The config_intrhook_establish() function schedules a function  to  be  run  after  interrupts  have  been
       enabled,  but before root is mounted.  If the system has already passed this point in its initialization,
       the function is called immediately.

       The config_intrhook_disestablish() function removes the entry from the hook queue.

       Before root is mounted, all the previously established hooks are run.  The boot process is  then  stalled
       until  all  handlers remove their hook from the hook queue with config_intrhook_disestablish().  The boot
       process then proceeds to attempt to mount the root file system.  Any driver that can potentially  provide
       devices  they  wish  to  be  mounted as root must use either this hook, or probe all these devices in the
       initial probe.  Since interrupts are disabled during the probe process, many drivers  need  a  method  to
       probe for devices with interrupts enabled.

       The requests are made with the intr_config_hook structure.  This structure is defined as follows:

       struct intr_config_hook {
               TAILQ_ENTRY(intr_config_hook) ich_links;/* Private */
               void    (*ich_func)(void *arg);         /* function to call */
               void    *ich_arg;                       /* Argument to call */
       };

       Storage  for  the intr_config_hook structure must be provided by the driver.  It must be stable from just
       before the hook is established until after the hook is disestablished.

       Specifically, hooks are run at SI_SUB_INT_CONFIG_HOOKS(), which is immediately  after  the  scheduler  is
       started, and just before the root file system device is discovered.

RETURN VALUES

       A zero return value means the hook was successfully added to the queue (with either deferred or immediate
       execution).   A  non-zero  return  value  means  the  hook could not be added to the queue because it was
       already on the queue.

SEE ALSO

       DEVICE_ATTACH(9)

HISTORY

       These functions were introduced in FreeBSD 3.0 with the CAM subsystem, but are available for  any  driver
       to use.

AUTHORS

       The  functions  were  written  by  Justin  Gibbs <gibbs@FreeBSD.org>.  This manual page was written by M.
       Warner Losh <imp@FreeBSD.org>.

Debian                                         September 24, 2006                             CONFIG_INTRHOOK(9)