freebsd-dev/sys/kern/subr_pcpu.c
John Baldwin 882bcf5879 Document the requirements and nature of the logical CPU IDs. It isn't
very strict and leaves much up to the platform so that it can define a
convenient mapping.

Requested by:	mjacob
2001-10-24 22:15:38 +00:00

76 lines
2.8 KiB
C

/*
* Copyright (c) 2001 Wind River Systems, Inc.
* All rights reserved.
* Written by: John Baldwin <jhb@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
/*
* This module provides MI support for per-cpu data.
*
* Each architecture determines the mapping of logical CPU IDs to physical
* CPUs. The requirements of this mapping are as follows:
* - Logical CPU IDs must reside in the range 0 ... MAXCPU - 1.
* - The mapping is not required to be dense. That is, there may be
* gaps in the mappings.
* - The platform sets the value of MAXCPU in <machine/param.h>.
* - It is suggested, but not required, that in the non-SMP case, the
* platform define MAXCPU to be 1 and define the logical ID of the
* sole CPU as 0.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/pcpu.h>
static struct globaldata *cpuid_to_globaldata[MAXCPU];
struct cpuhead cpuhead = SLIST_HEAD_INITIALIZER(cpuhead);
/*
* Register a struct globaldata.
*/
void
globaldata_register(struct globaldata *globaldata)
{
KASSERT(globaldata->gd_cpuid >= 0 && globaldata->gd_cpuid < MAXCPU,
("globaldata_register: invalid cpuid"));
cpuid_to_globaldata[globaldata->gd_cpuid] = globaldata;
SLIST_INSERT_HEAD(&cpuhead, globaldata, gd_allcpu);
}
/*
* Locate a struct globaldata by cpu id.
*/
struct globaldata *
globaldata_find(u_int cpuid)
{
return (cpuid_to_globaldata[cpuid]);
}