adriod HAL层 内核空间与用户空间内存共享

1、内核部分
unsigned long gMmapAddr;
unsigned long lMmapAddr;
 
static int xxx_mmap(struct file *filp, struct vm_area_struct *vma)
{
 vma->vm_pgoff = ((unsigned long)virt_to_phys(gMmapAddr)) >> PAGE_SHIFT;  
 
 printk("vma->vm_pgoff = %lx\n",vma->vm_pgoff); 
   
    if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, sizeof(gMmapAddr),  vma->vm_page_prot))  
 {
  printk("remap_pfn_range error\n");
  return -EAGAIN; 
 }
 return 0;
}
 
static int __init shareMmap_init(void)
{
   gMmapAddr  = PAGE_ALIGN((UINT32)lMmapAddr);//页对齐，重要
 
   return 0;
}
 
EXPORT_SYMBOL_GPL(gMmapAddr);
这后可以引用 gMmapAddr
 
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2、应用层
 
unsigned long *comAddr;
 
 //打开和共享内存驱动
  fd = open("/dev/map",O_RDWR);
 if (fd < 0)
 {
  return FALSE;
 }
 
 comAddr  = (unsigned long*)mmap(NULL, sizeof(unsigned long), PROT_READ | PROT_WRITE | PROT_EXEC, MAP_SHARED, fd, 0);