Messages in this thread | | | Subject | mmap RAM? | From | Neal Becker <> | Date | 24 Mar 1998 08:13:07 -0500 |
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I am trying to write a driver for a new device. It is an MPEG2 video *encoder*. The device sits on a PCI bus. It wants to DMA encoded video to the host RAM.
It would be convenient if the user program could read this data via mmap.
I have just bought Alessandro Rubini's new book "Linux Device Drivers". In it he says that remapping host RAM to user space is difficult. The remap_page_range won't work. He talks about the 'nopage method'. He gives an example, but the example is limited so single pages (I don't completely understand why).
My driver needs at least 128kb. (I'd really like 256kb, but I guess that's a problem). Assume I use get_free_pages to grab 128kb. How can this be accessed via mmap? Are there any examples?
Thanks.
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