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    SubjectRe: Can we move device drivers into user-space?
    On Fri, 24 Feb 2012 10:19:36 EST, Jidong Xiao said:

    > Actually, my major concern is, since UIO has been accepted, then why
    > don't we move all the rest device drivers into user space as well. As
    > I understand, currently, some of device drivers are running on user
    > space, while the other (or say the majority of) device drivers are
    > running on kernel space, so why don't we maintain a consistent device
    > drivers infrastructure, say, either all in user space, or all in
    > kernel space. (Sure some critical device drivers still need to be kept
    > in kernel space.)

    Sure we could do that, if you deal with all of the following issues:
    1) All I/O would take a lot more CPU, due to the additional context switching
    that would be required to start an I/O and handle the completion interrupt.
    2) It makes it a lot harder to do zero-copy I/O.
    3) Once we push the API to userspace, we're stuck with it. See
    Documentation/stable_api_nonsense.txt for the details.

    And finally:

    4) -ENOPATCH. You think it's a good idea, do up a patch that works at
    least as well as what we have now...
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      Last update: 2012-02-24 17:01    [W:0.020 / U:52.900 seconds]
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