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Annotation of XNU/osfmk/i386/cpu_number.h, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
                      3:  *
                      4:  * @APPLE_LICENSE_HEADER_START@
                      5:  * 
                      6:  * The contents of this file constitute Original Code as defined in and
                      7:  * are subject to the Apple Public Source License Version 1.1 (the
                      8:  * "License").  You may not use this file except in compliance with the
                      9:  * License.  Please obtain a copy of the License at
                     10:  * http://www.apple.com/publicsource and read it before using this file.
                     11:  * 
                     12:  * This Original Code and all software distributed under the License are
                     13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
                     14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
                     15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
                     16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
                     17:  * License for the specific language governing rights and limitations
                     18:  * under the License.
                     19:  * 
                     20:  * @APPLE_LICENSE_HEADER_END@
                     21:  */
                     22: /*
                     23:  * @OSF_COPYRIGHT@
                     24:  */
                     25: /* 
                     26:  * Mach Operating System
                     27:  * Copyright (c) 1991,1990 Carnegie Mellon University
                     28:  * All Rights Reserved.
                     29:  * 
                     30:  * Permission to use, copy, modify and distribute this software and its
                     31:  * documentation is hereby granted, provided that both the copyright
                     32:  * notice and this permission notice appear in all copies of the
                     33:  * software, derivative works or modified versions, and any portions
                     34:  * thereof, and that both notices appear in supporting documentation.
                     35:  * 
                     36:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
                     37:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
                     38:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
                     39:  * 
                     40:  * Carnegie Mellon requests users of this software to return to
                     41:  * 
                     42:  *  Software Distribution Coordinator  or  [email protected]
                     43:  *  School of Computer Science
                     44:  *  Carnegie Mellon University
                     45:  *  Pittsburgh PA 15213-3890
                     46:  * 
                     47:  * any improvements or extensions that they make and grant Carnegie Mellon
                     48:  * the rights to redistribute these changes.
                     49:  */
                     50: 
                     51: /*
                     52:  */
                     53: 
                     54: /*
                     55:  *     Machine-dependent definitions for cpu identification.
                     56:  *
                     57:  */
                     58: #ifndef        _I386_CPU_NUMBER_H_
                     59: #define        _I386_CPU_NUMBER_H_
                     60: 
                     61: extern int     cpu_number(void);
                     62: 
                     63: #ifdef MACH_KERNEL_PRIVATE
                     64: 
                     65: #include <platforms.h>
                     66: #include <cpus.h>
                     67: 
                     68: #include <mp_v1_1.h>
                     69: 
                     70: #if    MP_V1_1
                     71: #include <i386/apic.h>
                     72: #include <i386/asm.h>
                     73: 
                     74: extern int lapic_id;
                     75: 
                     76: extern __inline__ int cpu_number(void)
                     77: {
                     78:        register int cpu;
                     79: 
                     80:        __asm__ volatile ("movl " CC_SYM_PREFIX "lapic_id, %0\n"
                     81:                          "     movl 0(%0), %0\n"
                     82:                          "     shrl %1, %0\n"
                     83:                          "     andl %2, %0"
                     84:                    : "=r" (cpu)
                     85:                    : "i" (LAPIC_ID_SHIFT), "i" (LAPIC_ID_MASK));
                     86: 
                     87:        return(cpu);
                     88: }
                     89: #else  /* MP_V1_1 */
                     90: /*
                     91:  * At least one corollary cpu type does not have local memory at all.
                     92:  * The only way I found to store the cpu number was in some 386/486
                     93:  * system register. cr3 has bits 0, 1, 2 and 5, 6, 7, 8, 9, 10, 11
                     94:  * available. Right now we use 0, 1 and 2. So we are limited to 8 cpus.
                     95:  * For more cpus, we could use bits 5 - 11 with a shift.
                     96:  *
                     97:  * Even for other machines, like COMPAQ this is much faster the inb/outb
                     98:  * 4 cycles instead of 10 to 30.
                     99:  */
                    100: #if    defined(__GNUC__)
                    101: #if    NCPUS   > 8
                    102: #error cpu_number() definition only works for #cpus <= 8
                    103: #else
                    104: 
                    105: extern __inline__ int cpu_number(void)
                    106: {
                    107:        register int cpu;
                    108: 
                    109:        __asm__ volatile ("movl %%cr3, %0\n"
                    110:                "       andl $0x7, %0"
                    111:                    : "=r" (cpu));
                    112:        return(cpu);
                    113: }
                    114: #endif
                    115: #endif /* defined(__GNUC__) */
                    116: 
                    117: #endif /* MP_V1_1 */
                    118: 
                    119: #endif /* MACH_KERNEL_PRIVATE */
                    120: 
                    121: #endif /* _I386_CPU_NUMBER_H_ */

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