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    SubjectRe: [Scst-devel] [PATCH 8/19]: SCST SYSFS interface implementation
    On Fri, Nov 19, 2010 at 11:50:43PM +0300, Vladislav Bolkhovitin wrote:
    > Dmitry Torokhov, on 11/19/2010 11:22 PM wrote:
    > >> None of the SCST objects are Linux devices. None of them has entries in
    > >> /dev, none of them needs to send any events to udev and none of them
    > >> sends or receives data from DMA, hence has any DMA parameters or
    > >> restrictions. So, how can them fit into the driver/bus/device model you
    > >> are enforcing?
    > >
    > > Note that the entities in /sys/devices/... tree and not necessarily
    > > physical devices bit rather interface abstractionss. Consider, for
    > > example, /sys/class/input/*. None of the "devices" there talk directly
    > > to hardware, do DMA or other things. Some of them don't even talk to
    > > usrespace directly but rather through additional interfaces (evdev.
    > > mousedev, ect). Still they are represented there and even have suspend
    > > and resume methods (because even for logical devices it makes sense to
    > > save and restore some state).

    This is correct.

    > SCST devices are not even logical devices. As I wrote, "devices" word is
    > misleading. SCST devices are converse of what Linux means under this
    > word. SCST devices are like NFS exports: a place where those events
    > generated and those requests received.

    No, that's fine.

    > Think of SCST device as if it sits on the opposite side of the PCI bus
    > of the corresponding SCSI device Linux sees in /sys/class and /sys/bus.

    Again, that's fine, look at usb gadgets, it's the same thing.

    > So, if we need Linux devices for SCST devices, we create them using
    > scst_local driver. And then, of course, all them have their place in
    > /sys/class/ and /sys/bus.

    No, just /sys/bus/ which will cause them to become part of the big
    device tree in /sys/devices/

    Again, use this interface, it is what it is there for, to not use it is
    just wrong.

    good luck,

    greg k-h

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      Last update: 2010-11-19 22:21    [W:0.023 / U:8.776 seconds]
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