ldd3 Memory Mapping and DMA中remap_pfn_range的一点疑惑

hhb0331

书中page 449中：
The following does the trick for a driver mapping a region of
simple_region_size bytes, beginning at physical address simple_region_start (which
should be page-aligned): (注释为我的理解)

//off为设备上需要映射内存的偏移量(大小,单位字节)，相对于simple_region_start而言
unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
//设备映射内存的起始地址
unsigned long physical = simple_region_start + off;
//用户用于映射设备物理内存的虚拟内存大小
unsigned long vsize = vma->vm_end - vma->vm_start;
//可用于映射的物理内存的大小
unsigned long psize = simple_region_size - off;
if (vsize > psize)
return -EINVAL; /* spans too high */
remap_pfn_range(vma, vma_>vm_start, physical, vsize, vma->vm_page_prot);
我的问题是，remap_pfn_range的参数physical，是不是应该传入 physical>>PAGE_SHIFT,不应该是physical
希望大侠指教

hhb0331

上网查了一下该书的勘误，确实有错：

unsigned long physical = simple_region_start + off;
->
unsigned long pfn = page_to_pfn(simple_region_start + off);



remap_pfn_range(vma, vma_>vm_start, physical, vsize, vma->vm_page_prot);
->
remap_pfn_range(vma, vma->vm_start, pfn, vsize, vma->vm_page_prot);
不过页号好像不对，是429，可能是第二版的吧