1.\" Copyright (c) 2011 Alexander Motin <mav@FreeBSD.org> 2.\" All rights reserved. 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, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.Dd June 19, 2020 26.Dt APIC 4 27.Os 28.Sh NAME 29.Nm apic 30.Nd Advanced Programmable Interrupt Controller (APIC) driver 31.Sh SYNOPSIS 32This driver is a mandatory part of amd64 kernel. 33To compile this driver into i386 kernel, 34place the following line in your 35kernel configuration file: 36.Bd -ragged -offset indent 37.Cd "device apic" 38.Ed 39.Pp 40The following tunables are settable from the 41.Xr loader 8 : 42.Bl -ohang 43.It Va hint.apic. Ns Ar X Ns Va .clock 44controls event timers functionality support. 45Setting to 0, disables it. 46Default value is 1. 47.It Va hint.apic. Ns Ar X Ns Va .disabled 48Set this to 1 to disable APIC support, falling back to the legacy PIC. 49.El 50.Sh DESCRIPTION 51There are two components in the Intel APIC system, the local APIC (LAPIC) 52and the I/O APIC. 53There is one local APIC in each CPU in the system. 54There is typically one I/O APIC for each peripheral bus in the system. 55.Pp 56Local APICs manage all external interrupts for a specific processor. 57In addition, they are able to accept and generate inter-processor interrupts 58(IPIs). 59.Pp 60I/O APICs contain a redirection table, which is used to route the interrupts 61they receive from peripheral buses to one or more local APICs. 62.Pp 63Each local APIC includes one 32-bit programmable timer. 64This driver uses them to supply kernel with one event timer named "LAPIC". 65Event timer provided by the driver supports both one-shot and periodic modes. 66Because of local APIC nature it is per-CPU. 67The timer frequency is not reported by the platform and so automatically 68measured by the driver on the first use. 69Depending on CPU model this timer may stop in C3 and deeper CPU sleep states. 70Driver automatically adjusts event timer priority and reports it to prevent 71entering dangerous sleep states when it is used. 72.Sh SEE ALSO 73.Xr atrtc 4 , 74.Xr attimer 4 , 75.Xr eventtimers 4 , 76.Xr hpet 4 77