mm.h

用于汇编领域的,运用于OS的MAIN函数.基于硬件基础的源代码

#define PGSIZE (4*1024)  // 4K byte page
#define MAXPGFRAME 1024 // handle upto 4M RAM which is 1K page frames  
#define MAXDIR 1024 // max num of dir's per process. each dir can cover
                    // 1024 pages, and 1024 directories cover 4G addr space. 
					// Each directory can cover 1024*4K byte, that is
					// 4M byte. Since we use only 4M Ram, only dir 0 will
					// be active always.
#define MAXFRAME 1024 // max frames per page directory. each directory can
                       // cover 1024 frame locations
#define USER_PAGE 512 // page num where user process locates
#define USER_PROCESS_LOCATION 0x200000 //virtual addr for user process
#define mloc(x)  ((x) & 0xfffff000) //mask out flag bits to get memory location 
                               // of directory/page table entry
// following is taken from linux
#define __flush_tlb() \ 
   do {  \
      unsigned int tmpreg;   \
	  __asm__ __volatile__(  \
		 "movl %%cr3, %0;  # flush TLB \n" \
		 "movl %0, %%cr3;              \n" \
		 : "=r" (tmpreg)  \
		 :: "memory"); \
	} while (0)
/*
#define __flush_tlb_global() \ 
   do {  \
      unsigned int tmpreg;   \
	  __asm__ __volatile__(  \
	     "movl %1, %%cr4;  # turn off PGE \n" \
		 "movl %%cr3, %0;  # flush TLB \n" \
		 "movl %0, %%cr3;              \n" \
		 "movl %2, %%cr4;  # turn PGE back on \n" \
		 : "=&r" (tmpreg)  \
		 : "r" (mmu_cr4_features & ~X86_CR4_PGE), \
		   "r" (mmu_cr4_features)  \
		   : "memory"); \
	} while (0)
*/

struct mm_struct{
   unsigned long *pgdir;
};

struct vm_area_struct { //VMA
   struct mm_struct * vm_mm;
   unsigned long vm_start;
   unsigned long vm_end;
   struct vm_are_struct *vm_next;
};

struct page{ // 32 byte descriptor for each page frame
   int count; // 0 means free page frame
   struct page *next; 
   struct page *prev;
   unsigned long index; 
   int d1,d2,d3,d4; // padding
};

extern struct page mem_map[];