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⟩.