FreeBSD/Linux Kernel Cross Reference
sys/i386/mp_desc.h

     /* 
      * Mach Operating System
      * Copyright (c) 1991,1990 Carnegie Mellon University
      * All Rights Reserved.
      * 
      * Permission to use, copy, modify and distribute this software and its
      * documentation is hereby granted, provided that both the copyright
      * notice and this permission notice appear in all copies of the
      * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     * 
     * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     * 
     * Carnegie Mellon requests users of this software to return to
     * 
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     * 
     * any improvements or extensions that they make and grant Carnegie Mellon
     * the rights to redistribute these changes.
     */
    
    /*
     * HISTORY
     * $Log:        mp_desc.h,v $
     * Revision 2.3  91/05/14  16:12:24  mrt
     *      Correcting copyright
     * 
     * Revision 2.2  91/05/08  12:39:51  dbg
     *      Created.
     *      [91/03/21            dbg]
     * 
     */
    
    #ifndef _I386_MP_DESC_H_
    #define _I386_MP_DESC_H_
    
    #include <cpus.h>
    
    /*
     * Multiprocessor i386/i486 systems use a separate copy of the
     * GDT, IDT, LDT, and kernel TSS per processor.  The first three
     * are separate to avoid lock contention: the i386 uses locked
     * memory cycles to access the descriptor tables.  The TSS is
     * separate since each processor needs its own kernel stack,
     * and since using a TSS marks it busy.
     */
    
    #include <i386/seg.h>
    #include <i386/tss.h>
    
    /*
     * The descriptor tables are together in a structure
     * allocated one per processor (except for the boot processor).
     */
    struct mp_desc_table {
            struct fake_descriptor  idt[IDTSZ];     /* IDT */
            struct fake_descriptor  gdt[GDTSZ];     /* GDT */
            struct fake_descriptor  ldt[LDTSZ];     /* LDT */
            struct i386_tss         ktss;
    };
    
    /*
     * They are pointed to by a per-processor array.
     */
    extern struct mp_desc_table     *mp_desc_table[NCPUS];
    
    /*
     * The kernel TSS gets its own pointer.
     */
    extern struct i386_tss          *mp_ktss[NCPUS];
    
    /*
     * So does the GDT.
     */
    extern struct fake_descriptor   *mp_gdt[NCPUS];
    
    
    /*
     * Each CPU calls this routine to set up its descriptor tables.
     */
    extern struct mp_desc_table *   mp_desc_init(/* int */);
    
    #endif  /* _I386_MP_DESC_H_ */

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