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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