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.\" $FreeBSD$ 28.\" 29.Dd March 8, 2021 30.Dt CONFIG_INTRHOOK 9 31.Os 32.Sh NAME 33.Nm config_intrhook 34.Nd schedule a function to be run after interrupts have been enabled, 35but before root is mounted 36.Sh SYNOPSIS 37.In sys/kernel.h 38.Vt typedef void (*ich_func_t)(void *arg); 39.Ft int 40.Fn config_intrhook_establish "struct intr_config_hook *hook" 41.Ft void 42.Fn config_intrhook_disestablish "struct intr_config_hook *hook" 43.Ft int 44.Fn config_intrhook_drain "struct intr_config_hook *hook" 45.Ft void 46.Fn config_intrhook_oneshot "ich_func_t func" "void *arg" 47.Sh DESCRIPTION 48The 49.Fn config_intrhook_establish 50function schedules a function to be run after interrupts have been 51enabled, but before root is mounted. 52If the system has already passed this point in its initialization, 53the function is called immediately. 54.Pp 55The 56.Fn config_intrhook_disestablish 57function removes the entry from the hook queue. 58.Pp 59The 60.Fn config_intrhook_drain 61function removes the entry from the hook queue in a safe way. 62If the hook is not currently active it removes 63.Fa hook 64from the hook queue and returns 65.Vt ICHS_QUEUED . 66If the hook is active, it waits for the hook to complete before returning 67.Vt ICHS_RUNNING . 68If the hook has previously completed, it returns 69.Vt ICHS_DONE . 70Because a 71.Vt config_intrhook 72is undefined prior to 73.Fn config_intrhook_establish , 74this function may only be called after that function has returned. 75.Pp 76The 77.Fn config_intrhook_oneshot 78function schedules a function to be run as described for 79.Fn config_intrhook_establish ; 80the entry is automatically removed from the hook queue 81after that function runs. 82This is appropriate when additional device configuration must be done 83after interrupts are enabled, but there is no need to stall the 84boot process after that. 85This function allocates memory using M_WAITOK; do not call this while 86holding any non-sleepable locks. 87.Pp 88Before root is mounted, all the previously established hooks are 89run. 90The boot process is then stalled until all handlers remove their hook 91from the hook queue with 92.Fn config_intrhook_disestablish . 93The boot process then proceeds to attempt to mount the root file 94system. 95Any driver that can potentially provide devices they wish to be 96mounted as root must use either this hook, or probe all these devices 97in the initial probe. 98Since interrupts are disabled during the probe process, many drivers 99need a method to probe for devices with interrupts enabled. 100.Pp 101The requests are made with the 102.Vt intr_config_hook 103structure. 104This structure is defined as follows: 105.Bd -literal 106struct intr_config_hook { 107 TAILQ_ENTRY(intr_config_hook) ich_links;/* Private */ 108 ich_func_t ich_func; /* function to call */ 109 void *ich_arg; /* Argument to call */ 110}; 111.Ed 112.Pp 113Storage for the 114.Vt intr_config_hook 115structure must be provided by the driver. 116It must be stable from just before the hook is established until 117after the hook is disestablished. 118.Pp 119Specifically, hooks are run at 120.Fn SI_SUB_INT_CONFIG_HOOKS , 121which is immediately after the scheduler is started, 122and just before the root file system device is discovered. 123.Sh RETURN VALUES 124A zero return value means the hook was successfully added to the queue 125(with either deferred or immediate execution). 126A non-zero return value means the hook could not be added to the queue 127because it was already on the queue. 128.Sh SEE ALSO 129.Xr DEVICE_ATTACH 9 130.Sh HISTORY 131These functions were introduced in 132.Fx 3.0 133with the CAM subsystem, but are available for any driver to use. 134.Sh AUTHORS 135.An -nosplit 136The functions were written by 137.An Justin Gibbs Aq Mt gibbs@FreeBSD.org . 138This manual page was written by 139.An M. Warner Losh Aq Mt imp@FreeBSD.org . 140