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    SubjectRe: Vramfs: filesystem driver to utilize extra RAM on VGA devices
    Every VGA device connected to the PCI bus has resources that are known 
    to the Linux kernel. One of the memory resources is the video RAM
    (always the largest prefetchable resource listed), with the base and
    length known to the PCI subsystem. So, all vramfs needs on mount is the
    PCI device, and the mountpoint, and it can dole it out to userspace.
    Reading and writing is handled with ioremap(). mmap() is handled by
    directly mmaping() that VRAM into user-space (just like /dev/fb0). Files
    are recorded in system memory as a list of entities with a starting
    block and length, so no fragmentation is possible.

    No communication with the GPU is needed to do this, it's possible to use
    VRAM this way even on devices that nobody in the system knows how to
    talk to.
    > How do you accomplish that?
    > (I haven't yet looked at your code...)
    > -PWM

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      Last update: 2009-01-29 18:33    [W:0.021 / U:0.868 seconds]
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