《深入理解LINUX内存管理》学习笔记(3)

#define MAX_PHYSMEM_BITS 36 #else

#define SECTION_SIZE_BITS 26 #define MAX_PHYSADDR_BITS 32 #define MAX_PHYSMEM_BITS 32

#endifinclude/linux/mmzone.h:#define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)#define NR_MEM_SECTIONS (1UL << SECTIONS_SHIFT)#ifdef CONFIG_SPARSEMEM_EXTREME

#define SECTIONS_PER_ROOT (PAGE_SIZE / sizeof (struct mem_section)) #else

#define SECTIONS_PER_ROOT 1

#endif#define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)

#define NR_SECTION_ROOTS (NR_MEM_SECTIONS / SECTIONS_PER_ROOT) #define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1) 首先声明了一个全局的mem_section的全局数组。

struct mem_section *mem_section[NR_SECTION_ROOTS]；

调用sparse_add_one_section()函数，分配mem_section，并且初始化。