On Sun, Mar 10, 2013 at 11:30 PM, Christoph Seitz <c.se...@tu-bs.de> wrote:
> Hi all, > > I have some problems allocation Memory the right way and use it in my > kernel module. > > I use a char device for reading and writing from/to a pcie dma card. > Especially the read function makes me some headache. The user allocates > some memory with posix_memalign and call the read function on the > device, so that the devices knows where to write to. My driver now uses > get_user_pages() to pin the user pages. The memory has never been > written or read by the user, so it's not yet in the RAM, right? And > get_user_pages returns a valid number of pages, but for every page the > same struct. (respectively the same pointer). Is there any way to ensure > that the user pages are in the ram and get_user_pages returns a valid > page array? > If you know the RAM physical address range you can figure out by doing the following *page_to_pfn(page_ptr) << 12*; where page_ptr is a struct page * returned by get_user_pages(). * page_to_pfn()* will return the pfn of the corresponding page frame and left shifting by 12 bits will give you page frame base address. > Regards > Chris > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > -- Regards, Prabhunath G Linux Trainer Bangalore
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