Date: Tue, 17 Feb 2009 08:54:24 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: hselasky@c2i.net Cc: freebsd-usb@FreeBSD.org Subject: Re: USB2+umass: root mount fails Message-ID: <20090217.085424.775975548.imp@bsdimp.com> In-Reply-To: <200902170856.11631.hselasky@c2i.net> References: <20090216.190312.1756925299.imp@bsdimp.com> <7F91349C-7E58-47C8-BB69-3B2F391B4E73@mac.com> <200902170856.11631.hselasky@c2i.net>
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In message: <200902170856.11631.hselasky@c2i.net>
Hans Petter Selasky <hselasky@c2i.net> writes:
: On Tuesday 17 February 2009, Marcel Moolenaar wrote:
: > On Feb 16, 2009, at 6:03 PM, M. Warner Losh wrote:
: > > : root_mount_hold() and root_mount_rel() are specifically
: > > : designed to inform the mountroot code that it needs to
: > > : wait (or that it should go ahead and mount root).
: > >
: > > But it looks like the old usb code didn't call it either... I think
: > > old code enumerated right away during boot, while the new code defers
: > > the enumeration until events can be processed...
: >
: > Yes, you're right. USB1 used the following:
: >
: > SYSINIT(usb_cold_explore, SI_SUB_CONFIGURE, SI_ORDER_MIDDLE,
: > usb_cold_explore, NULL);
: >
: > SI_SUB_CONFIGURE didn't complete before all USB busses
: > were enumerated.
:
: I would really prefer that first time USB enumeration is not synchronous. This
: has to do with startup timing. It simply wastes a lot of time to wait for all
: the busses to be probed in serial. Sure it works nice with a USB keyboard and
: a USB mouse, but when you have a couple of USB HUBs and +8 devices connected,
: it simply speeds up the boot time so that you reach the root prompt by the
: time you would else have done the mount root mfs.
:
: If the mountroot code cannot find the disk, it should sleep and loop.
I think this is a weak argument. I'm strongly in favor of the usb1
behavior here.
Warner
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