1.\" 2.\" Copyright (C) 2006 M. Warner Losh <imp@FreeBSD.org> 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 16.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 19.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 20.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 25.\" DAMAGE. 26.\" 27.Dd March 8, 2021 28.Dt CONFIG_INTRHOOK 9 29.Os 30.Sh NAME 31.Nm config_intrhook 32.Nd schedule a function to be run after interrupts have been enabled, 33but before root is mounted 34.Sh SYNOPSIS 35.In sys/kernel.h 36.Vt typedef void (*ich_func_t)(void *arg); 37.Ft int 38.Fn config_intrhook_establish "struct intr_config_hook *hook" 39.Ft void 40.Fn config_intrhook_disestablish "struct intr_config_hook *hook" 41.Ft int 42.Fn config_intrhook_drain "struct intr_config_hook *hook" 43.Ft void 44.Fn config_intrhook_oneshot "ich_func_t func" "void *arg" 45.Sh DESCRIPTION 46The 47.Fn config_intrhook_establish 48function schedules a function to be run after interrupts have been 49enabled, but before root is mounted. 50If the system has already passed this point in its initialization, 51the function is called immediately. 52.Pp 53The 54.Fn config_intrhook_disestablish 55function removes the entry from the hook queue. 56.Pp 57The 58.Fn config_intrhook_drain 59function removes the entry from the hook queue in a safe way. 60If the hook is not currently active it removes 61.Fa hook 62from the hook queue and returns 63.Vt ICHS_QUEUED . 64If the hook is active, it waits for the hook to complete before returning 65.Vt ICHS_RUNNING . 66If the hook has previously completed, it returns 67.Vt ICHS_DONE . 68Because a 69.Vt config_intrhook 70is undefined prior to 71.Fn config_intrhook_establish , 72this function may only be called after that function has returned. 73.Pp 74The 75.Fn config_intrhook_oneshot 76function schedules a function to be run as described for 77.Fn config_intrhook_establish ; 78the entry is automatically removed from the hook queue 79after that function runs. 80This is appropriate when additional device configuration must be done 81after interrupts are enabled, but there is no need to stall the 82boot process after that. 83This function allocates memory using M_WAITOK; do not call this while 84holding any non-sleepable locks. 85.Pp 86Before root is mounted, all the previously established hooks are 87run. 88The boot process is then stalled until all handlers remove their hook 89from the hook queue with 90.Fn config_intrhook_disestablish . 91The boot process then proceeds to attempt to mount the root file 92system. 93Any driver that can potentially provide devices they wish to be 94mounted as root must use either this hook, or probe all these devices 95in the initial probe. 96Since interrupts are disabled during the probe process, many drivers 97need a method to probe for devices with interrupts enabled. 98.Pp 99The requests are made with the 100.Vt intr_config_hook 101structure. 102This structure is defined as follows: 103.Bd -literal 104struct intr_config_hook { 105 TAILQ_ENTRY(intr_config_hook) ich_links;/* Private */ 106 ich_func_t ich_func; /* function to call */ 107 void *ich_arg; /* Argument to call */ 108}; 109.Ed 110.Pp 111Storage for the 112.Vt intr_config_hook 113structure must be provided by the driver. 114It must be stable from just before the hook is established until 115after the hook is disestablished. 116.Pp 117Specifically, hooks are run at 118.Fn SI_SUB_INT_CONFIG_HOOKS , 119which is immediately after the scheduler is started, 120and just before the root file system device is discovered. 121.Sh RETURN VALUES 122A zero return value means the hook was successfully added to the queue 123(with either deferred or immediate execution). 124A non-zero return value means the hook could not be added to the queue 125because it was already on the queue. 126.Sh SEE ALSO 127.Xr DEVICE_ATTACH 9 128.Sh HISTORY 129These functions were introduced in 130.Fx 3.0 131with the CAM subsystem, but are available for any driver to use. 132.Sh AUTHORS 133.An -nosplit 134The functions were written by 135.An Justin Gibbs Aq Mt gibbs@FreeBSD.org . 136This manual page was written by 137.An M. Warner Losh Aq Mt imp@FreeBSD.org . 138