Date: Fri, 15 Aug 2003 12:25:18 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: eaja@erols.com Cc: gurney_j@efn.org Subject: Re: usbd does not use detach Message-ID: <20030815.122518.05878262.imp@bsdimp.com> In-Reply-To: <20030815111809.06960905.eaja@erols.com> References: <20030814110113.4d238ddd.eaja@erols.com> <20030814173807.GR10708@funkthat.com> <20030815111809.06960905.eaja@erols.com>
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In message: <20030815111809.06960905.eaja@erols.com>
Eric Jacobs <eaja@erols.com> writes:
: On Thu, 14 Aug 2003 10:38:07 -0700
: John-Mark Gurney <gurney_j@efn.org> wrote:
:
: >
: > This is a bit more complex than this. There are many more layers between
: > usb and VFS. For USB umass devices, they proxy to cam, which then is an
: > interface to da which is a provider for geom which then provides the
: > final device for ufs to mount. So, each and every one of those steps
: > need to be taught about this. Right now, very few things use newbus
: > even though they should. This is a problem of them existing before
: > newbus was nailed down. CAM doesn't use newbus for any of it's device
: > management (scsi device, not HBA attachment).
:
: Yes, I'm aware that there are more layers. Propogating the flag value
: down is trivial. The major deficiency of CAM and GEOM is that errors
: can't be sent back up. For example, we have this scenario:
:
: # mount /dev/da0s1a /mnt # mounting a USB hard drive
: # cd /mnt # in use
: # kldunload umass # oops! it succeeds
: #
:
: Ideally, I'd love to see an enhanced newbus provide the One True
: Framework for attaching and detaching both devices and device
: clients. Unfortunately, it seems like it would take a substantial
: redesign to get there from this point.
Nah, just to make cam use it. cam and newbus were contemporary
developments, so cam used the old ad-hoc way of dealing.
Warner
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