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shutdownhook_disestablish(9) [netbsd man page]


shutdownhook_establish, shutdownhook_disestablish -- add or remove a shutdown hook SYNOPSIS
void * shutdownhook_establish(void (*fn)(void *), void *arg); void shutdownhook_disestablish(void *cookie); DESCRIPTION
The shutdownhook_establish API is deprecated. The shutdownhook_establish() function adds fn to the list of hooks invoked by doshutdownhooks(9) at shutdown. When invoked, the hook func- tion fn will be passed arg as its only argument. The shutdownhook_disestablish() function removes the hook described by the opaque pointer cookie from the list of hooks to be invoked at shutdown. If cookie is invalid, the result of shutdownhook_disestablish() is undefined. Shutdown hooks should be used to perform one-time activities that must happen immediately before the kernel exits. Because of the environ- ment in which they are run, shutdown hooks cannot rely on many system services (including file systems, and timeouts and other interrupt- driven services), or even basic system integrity (because the system could be rebooting after a crash). RETURN VALUES
If successful, shutdownhook_establish() returns an opaque pointer describing the newly-established shutdown hook. Otherwise, it returns NULL. EXAMPLES
It may be appropriate to use a shutdown hook to disable a device that does direct memory access, so that the device will not try to access memory while the system is rebooting. It may be appropriate to use a shutdown hook to inform watchdog timer hardware that the operating system is no longer running. SEE ALSO
doshutdownhooks(9) BUGS
The names are clumsy, at best. BSD
May 14, 2009 BSD

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CONFIG_INTRHOOK(9)					   BSD Kernel Developer's Manual					CONFIG_INTRHOOK(9)

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 ini- tial 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
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 <>. This manual page was written by M. Warner Losh <>. BSD
September 24, 2006 BSD
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