This is xnu-8019. See this file in:
/*
 * Copyright (c) 2003-2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#ifndef LIBKERN_SYSCTL_H
#define LIBKERN_SYSCTL_H

#include <sys/cdefs.h>

__BEGIN_DECLS

#include <sys/types.h>

/*
 * These are the support HW selectors for sysctlbyname.  Parameters that are byte counts or frequencies are 64 bit numbers.
 * All other parameters are 32 bit numbers.
 *
 *   hw.memsize                - The number of bytes of physical memory in the system.
 *
 *   hw.ncpu                   - The maximum number of processors that could be available this boot.
 *                               Use this value for sizing of static per processor arrays; i.e. processor load statistics.
 *
 *   hw.activecpu              - The number of processors currently available for executing threads.
 *                               Use this number to determine the number threads to create in SMP aware applications.
 *                               This number can change when power management modes are changed.
 *
 *   hw.physicalcpu            - The number of physical processors available in the current power management mode.
 *   hw.physicalcpu_max        - The maximum number of physical processors that could be available this boot
 *
 *   hw.logicalcpu             - The number of logical processors available in the current power management mode.
 *   hw.logicalcpu_max         - The maximum number of logical processors that could be available this boot
 *
 *   hw.tbfrequency            - This gives the time base frequency used by the OS and is the basis of all timing services.
 *                               In general is is better to use mach's or higher level timing services, but this value
 *                               is needed to convert the PPC Time Base registers to real time.
 *
 *   hw.cpufrequency           - These values provide the current, min and max cpu frequency.  The min and max are for
 *   hw.cpufrequency_max       - all power management modes.  The current frequency is the max frequency in the current mode.
 *   hw.cpufrequency_min       - All frequencies are in Hz.
 *
 *   hw.busfrequency           - These values provide the current, min and max bus frequency.  The min and max are for
 *   hw.busfrequency_max       - all power management modes.  The current frequency is the max frequency in the current mode.
 *   hw.busfrequency_min       - All frequencies are in Hz.
 *
 *   hw.cputype                - These values provide the mach-o cpu type and subtype.  A complete list is in <mach/machine.h>
 *   hw.cpusubtype             - These values should be used to determine what processor family the running cpu is from so that
 *                               the best binary can be chosen, or the best dynamic code generated.  They should not be used
 *                               to determine if a given processor feature is available.
 *   hw.cputhreadtype          - This value will be present if the processor supports threads.  Like hw.cpusubtype this selector
 *                               should not be used to infer features, and only used to name the processors thread architecture.
 *                               The values are defined in <mach/machine.h>
 *
 *   hw.byteorder              - Gives the byte order of the processor.  4321 for big endian, 1234 for little.
 *
 *   hw.pagesize               - Gives the size in bytes of the pages used by the processor and VM system.
 *
 *   hw.cachelinesize          - Gives the size in bytes of the processor's cache lines.
 *                               This value should be use to control the strides of loops that use cache control instructions
 *                               like dcbz, dcbt or dcbst.
 *
 *   hw.l1dcachesize           - These values provide the size in bytes of the L1, L2 and L3 caches.  If a cache is not present
 *   hw.l1icachesize           - then the selector will return and error.
 *   hw.l2cachesize            -
 *   hw.l3cachesize            -
 *
 *
 * These are the selectors for optional processor features.  Selectors that return errors are not support on the system.
 * Supported features will return 1 if they are recommended or 0 if they are supported but are not expected to help performance.
 * Future versions of these selectors may return larger values as necessary so it is best to test for non zero.
 *
 *   hw.optional.floatingpoint - Floating Point Instructions
 *   hw.optional.altivec       - AltiVec Instructions
 *   hw.optional.graphicsops   - Graphics Operations
 *   hw.optional.64bitops      - 64-bit Instructions
 *   hw.optional.fsqrt         - HW Floating Point Square Root Instruction
 *   hw.optional.stfiwx        - Store Floating Point as Integer Word Indexed Instructions
 *   hw.optional.dcba          - Data Cache Block Allocate Instruction
 *   hw.optional.datastreams   - Data Streams Instructions
 *   hw.optional.dcbtstreams   - Data Cache Block Touch Steams Instruction Form
 *
 */

/*
 * Sysctl handling
 */
#ifdef XNU_KERNEL_PRIVATE
int     kernel_sysctlbyname(const char *, void *, size_t *, void *, size_t);
#else
int     sysctlbyname(const char *, void *, size_t *, void *, size_t);
#endif

__END_DECLS

#endif  /* LIBKERN_SYSCTL_H */