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DMA memory mapping

I am developing a framegrabber driver.  I need to map memory for the 
grabber to DMA the images into.  I have it working currently where the 
grab happens into kernel memory and then I copy_to_user to get the 
buffer into user space.  I think I can eliminate this step by using 
remap_page_range which would allow me to access the grabbed images 
directly from user space.  The argument to remap_page_range that I don't 
understand is the first argument...the virtual address.  I know how big 
the buffer is, I know the physical address of the buffer allocated in 
the kernel, I have to set the protection such that the pages are not 
swapped...how do I get a virtual address to pass to the driver so that 
this mapping can take place?

TIA

-- 
Best regards,
David Stroupe
Keyed-Up Software


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