1 /* map.h 4.7 81/11/08 */ 2 3 /* 4 * Resource Allocation Maps. 5 * 6 * Associated routines manage sub-allocation of an address space using 7 * an array of segment descriptors. The first element of this array 8 * is a map structure, describing the arrays extent and the name 9 * of the controlled object. Each additional structure represents 10 * a free segment of the address space. 11 * 12 * A call to rminit initializes a resource map and may also be used 13 * to free some address space for the map. Subsequent calls to rmalloc 14 * and rmfree allocate and free space in the resource map. If the resource 15 * map becomes too fragmented to be described in the available space, 16 * then some of the resource is discarded. This may lead to critical 17 * shortages, but is better than not checking (as the previous versions 18 * of these routines did) or giving up and calling panic(). The routines 19 * could use linked lists and call a memory allocator when they run 20 * out of space, but that would not solve the out of space problem when 21 * called at interrupt time. 22 * 23 * N.B.: The address 0 in the resource address space is not available 24 * as it is used internally by the resource map routines. 25 */ 26 struct map { 27 struct mapent *m_limit; /* address of last slot in map */ 28 char *m_name; /* name of resource */ 29 /* we use m_name when the map overflows, in warning messages */ 30 }; 31 struct mapent 32 { 33 int m_size; /* size of this segment of the map */ 34 int m_addr; /* resource-space addr of start of segment */ 35 }; 36 37 #ifdef KERNEL 38 struct map *swapmap; 39 int nswapmap; 40 struct map *argmap; 41 #define ARGMAPSIZE 16 42 struct map *kernelmap; 43 struct map *mbmap; 44 #endif 45