使用nopage方法重新映射RAM

在驱动程序中，使用remap_pfn_range函数映射内存中的保留页（如X86系统中的640KB~1MB区域）和设备IO内存。而使用nopage函数来映射RAM。static char data[PAGE_SIZE];void scullp_vma_open(struct vm_area_struct *vma) { }void scullp_vma_close(struct vm_area_struct *vma) { }struct page *scullp_vma_nopage(struct vm_area_struct *vma, unsigned long address, int *type){ struct page *page = NOPAGE_SIGBUS; void *pageptr = NULL; offset = (address - vma->vm_start) + (vma->vm_pgoff << PAGE_OFFSET); offset >>= PAGE_SHIFT; pageptr = data[offset]; page = virt_to_page(pageptr); get_page(page); if(type)*type = VM_FAULT_MINOR; return page;}static struct vm_operations_struct scullp_vma_ops = { .open = scullp_vma_open, .close = scullp_vma_close, .nopage = scullp_vma_nopage,};static int scullp_mmap(struct file *filp, struct vm_area_struct *vma){ vma->vm_ops = &scullp_vma_ops; vma->vm_flags |= VM_RESERVED; vma->vm_private_data = filp->private_data; mpeg2tv_vma_open(vma); return 0;}