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    SubjectRe: firmware separation filesystem (fwfs)
    On Wed, Apr 16, 2003 at 04:47:09PM +0100, Alan Cox wrote:
    > On Mer, 2003-04-16 at 17:36, Manuel Estrada Sainz wrote:
    > > On the other hand, there are already many drivers in the kernel that
    > > include firmware in headers, keyspan, io_edgeport, dabusb, ser_a2232,
    > > sym53c8xx_2, ...
    > But so would loading it from hotplug via ioctl. It might be we want
    > a clean hotplug way to ask for 'firmare for xyz'.

    True, but ioctl()s are horrid. And the driver needs to set up a
    suitable device to which the ioctl() is applied, and deal with binding
    the right image to the right instance, which can get messy in some
    cases. As I see it the chief purpose of fwfs, or an equivalent sysfs
    formulation would be to provide a clean mechanism for passing firmware
    images to the kernel - figuring out which image to provide and
    supplying it at the relevant moment can and should be the job of
    hotplug or a similar userland helper.

    Incidentally another approach that also avoids nasty ioctl()s would be
    to invoke the userland helper with specially set up FD 1, which lets
    the kernel capture the program's stdout. When the driver needs a
    firmware it invokes the helper, which figures out the relevant image
    from its parameters and cats it. The driver (presumably sleeping
    waiting for this) grabs the image, stuffs it into the hardware, then
    throws it away.

    David Gibson | For every complex problem there is a | solution which is simple, neat and
    | wrong.
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