Date: Wed, 18 Feb 2009 21:02:00 -0800 From: Andrew Thompson <thompsa@FreeBSD.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-usb@FreeBSD.org Subject: Re: USB2+umass: root mount fails Message-ID: <20090219050200.GA84647@citylink.fud.org.nz> In-Reply-To: <20090217.085424.775975548.imp@bsdimp.com> References: <20090216.190312.1756925299.imp@bsdimp.com> <7F91349C-7E58-47C8-BB69-3B2F391B4E73@mac.com> <200902170856.11631.hselasky@c2i.net> <20090217.085424.775975548.imp@bsdimp.com>
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On Tue, Feb 17, 2009 at 08:54:24AM -0700, M. Warner Losh wrote: > In message: <200902170856.11631.hselasky@c2i.net> > Hans Petter Selasky <hselasky@c2i.net> writes: > : On Tuesday 17 February 2009, Marcel Moolenaar wrote: > : > > 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. I think its slightly more complex that adding a cold explore task. Most of the USB2 periperhel drivers defer a portion of their attach to a thread task, a change which needs to be reverted first. As others have said both the probe and attach must be synchronous. Andrew
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