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Annotation of 43BSDTahoe/sys/h/map.h, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1982, 1986 Regents of the University of California.
                      3:  * All rights reserved.  The Berkeley software License Agreement
                      4:  * specifies the terms and conditions for redistribution.
                      5:  *
                      6:  *     @(#)map.h       7.2 (Berkeley) 6/6/87
                      7:  */
                      8: 
                      9: /*
                     10:  * Resource Allocation Maps.
                     11:  *
                     12:  * Associated routines manage sub-allocation of an address space using
                     13:  * an array of segment descriptors.  The first element of this array
                     14:  * is a map structure, describing the arrays extent and the name
                     15:  * of the controlled object.  Each additional structure represents
                     16:  * a free segment of the address space.
                     17:  *
                     18:  * A call to rminit initializes a resource map and may also be used
                     19:  * to free some address space for the map.  Subsequent calls to rmalloc
                     20:  * and rmfree allocate and free space in the resource map.  If the resource
                     21:  * map becomes too fragmented to be described in the available space,
                     22:  * then some of the resource is discarded.  This may lead to critical
                     23:  * shortages, but is better than not checking (as the previous versions
                     24:  * of these routines did) or giving up and calling panic().  The routines
                     25:  * could use linked lists and call a memory allocator when they run
                     26:  * out of space, but that would not solve the out of space problem when
                     27:  * called at interrupt time.
                     28:  *
                     29:  * N.B.: The address 0 in the resource address space is not available
                     30:  * as it is used internally by the resource map routines.
                     31:  */
                     32: struct map {
                     33:        struct  mapent *m_limit;        /* address of last slot in map */
                     34:        char    *m_name;                /* name of resource */
                     35: /* we use m_name when the map overflows, in warning messages */
                     36: };
                     37: struct mapent
                     38: {
                     39:        int     m_size;         /* size of this segment of the map */
                     40:        int     m_addr;         /* resource-space addr of start of segment */
                     41: };
                     42: 
                     43: #ifdef KERNEL
                     44: struct map *swapmap;
                     45: int    nswapmap;
                     46: struct map *argmap;
                     47: #define        ARGMAPSIZE      16
                     48: struct map *kernelmap;
                     49: struct map *mbmap;
                     50: struct map *kmemmap;
                     51: #endif

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