Messages in this thread | | | Date | Mon, 23 Aug 2004 16:45:13 -0400 | From | Chris Friesen <> | Subject | question on char driver mmap |
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I have a need for a device driver to map a page of memory between interrupt handlers and userspace. It's been suggested that I use something like the following code (simplified):
unsigned long mypage;
int my_mmap(struct file *filp, struct vm_area_struct *vma) { unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
if (offset & ~PAGE_MASK) return -ENXIO;
mypage = __get_free_page(GFP_KERNEL); SetPageReserved(virt_to_page(mypage)); remap_page_range(vma->vm_start, virt_to_phys((void *) mypage), PAGE_SIZE, vma->vm_page_prot); return 0; }
This seems to work. If I do this, however, do I need to hook into the munmap() file operations to handle unmapping, clearing the reserved bit, and freeing the page, or will the memory subsystem do it for me?
Thanks,
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