Date: Mon, 16 Feb 2009 17:35:44 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: xcllnt@mac.com Cc: usb@freebsd.org Subject: Re: USB2+umass: root mount fails Message-ID: <20090216.173544.1555327603.imp@bsdimp.com> In-Reply-To: <741FAA3B-B91A-4A23-B47F-21141A8D0B5D@mac.com> References: <ACB7DFF1-6C8E-4936-9BD9-BB2FD375F3BB@mac.com> <20090216.161346.1176917525.imp@bsdimp.com> <741FAA3B-B91A-4A23-B47F-21141A8D0B5D@mac.com>
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In message: <741FAA3B-B91A-4A23-B47F-21141A8D0B5D@mac.com> Marcel Moolenaar <xcllnt@mac.com> writes: : : On Feb 16, 2009, at 3:13 PM, M. Warner Losh wrote: : : > In message: <ACB7DFF1-6C8E-4936-9BD9-BB2FD375F3BB@mac.com> : > Marcel Moolenaar <xcllnt@mac.com> writes: : > : Before I dig into the code, what's the current status of : > : root mounts on USB mass storage devices? : > : > First, there's a kludge-o-round that is similar to your "sleep 10" : > that you've added. It loops waiting for more devices to show up if : > the desired root file system hasn't appeared yet. : > : > There's no way for hot-plug busses to tell the kernel "I've tried my : > best to enumerate everything on my bus, and I'm done" : : Of course there is. Any and all USB hubs have a certain : number of ports. You can trivially iterate over all of : them and declare completion when you've tried them all. The hot-plug busses know. The mountroot code doesn't have a way to wait for the hot-plug busses. : Recursion is also not a big deal. When you find a HUB : underneath a port, you iterate over all the ports of : that downstream hub before you declare completion of : the USB discovery process. : : When the USB discovery process is done, you release : the root mount lock... : : So what's the problem? You're looking on the wrong side of the problem. Warner
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