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    SubjectRe: [PATCH v3] uio/pdrv_genirq: Add OF support
    On Tuesday 19 April 2011, Grant Likely wrote:
    > On Tue, Apr 19, 2011 at 11:58:25AM +1000, John Williams wrote:
    > >
    > > I know the arguments against the 'generic-uio' tag, but come on, let's
    > > look at the lesser of two evils here! I call BS on this DTS purity.

    Both a specific device ID and something like "generic-uio" are
    equally broken:

    If you have generic-uio, it is impossible to write an in-kernel driver
    for the same hardware without changing the device tree, meaning that
    it is impossible to correctly describe the hardware in the device tree.

    If you put a meaningful identifier into the match table, it is also
    impossible to have an in-kernel driver for the hardware, because now
    you have no way to choose whether to handle the device with UIO
    or an in-kernel driver.

    There may be cases where you have two instances of the same device
    in a machine and want one of them to be driven by UIO and the other
    by another driver. A common example of this would be a virtual machine
    where one device is passed through to the guest and the other is
    used by the host. I've done this for USB input devices and PCI network

    > Call it what you like, but the reasons are well founded. The alternative
    > that has been proposed which I am in agreement with is to investigate
    > giving userspace the hook to tell the kernel at runtime which devices
    > should be picked up by the uio driver.

    Yes, I believe this is the best option.

    > In the mean time, explicitly modifying the match table is an okay
    > compromise.



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