FreeBSD 7.0 manual page repository

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config_intrhook - schedule a function to be run after interrupts have



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


      #include <sys/kernel.h>
      config_intrhook_establish(struct intr_config_hook *hook);
      config_intrhook_disestablish(struct intr_config_hook *hook);


      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 pro‐
      cess 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 struc‐
      ture 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 imme‐
      diately after the scheduler is started, and just before the root file
      system device is discovered.
      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.


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


      The functions were written by Justin Gibbs 〈〉.  This
      manual page was written by M. Warner Losh 〈〉.


Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.