Re: Reattach/redetect allways connected umass device - is it possible ?

From: Bernd Walter (ticso_at_cicely12.cicely.de)
Date: 03/29/05

  • Next message: Stijn Hoop: "Re: Reattach/redetect allways connected umass device - is it possible ?" 
    Date: Tue, 29 Mar 2005 12:45:51 +0200
To: Julian Elischer <julian@elischer.org>

    On Tue, Mar 29, 2005 at 02:22:24AM -0800, Julian Elischer wrote:
    >
    >
    > M. Warner Losh wrote:
    >
    > >In message: <39800.1112083716@critter.freebsd.dk>
    > > "Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
    > >: In message <20050329.010433.66709025.imp@bsdimp.com>, "M. Warner Losh"
    > >writes:
    > >:
    > >: >: Only partial.
    > >: >
    > >: >You should be getting a change notification on the first access after
    > >: >the change happens...
    > >:
    > >: Right, that's what I mean by "partial". Full support would be an
    > >interrupt
    > >: when a media is removed or inserted.
    > >
    > >And what hardware, apart from PC Card, actually supports this?
    > >
    > >
    >
    > well, back to the original argument.... usb and firewire devices do..

    No - you can't insert media directly into usb or firewire.
    You always need a usb/firewire drive in between - usb/firewire are
    not drives - they are busses.
    Ever tried to get a CF media directly into your USB plug?
    No USB drive will contact you on media exchange - USB has no usefull
    mechanism for a device to contact the host.

    PC Card can be seen differently.
    Current PC Card usually implement an ata drive, but older JEDEC
    flash cards do not.
    But since we don't create a JEDEC drive instance independend of
    media existence this is more an academic view.
    In real world we see drive insert/eject with PC Card too.
    There is no drive without anything inserted.

    There are also points were things are not so obvious on the first look.
    CF ist one example.
    Technically it builds a whole ata drive in all three modes.
    But if we use it in an USB flash card reader we have to handle it
    as a media in a USB drive. 

    -- 
B.Walter                   BWCT                http://www.bwct.de
bernd@bwct.de                                  info@bwct.de
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  • Next message: Stijn Hoop: "Re: Reattach/redetect allways connected umass device - is it possible ?"

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