USB2: booting from usb memory issue, including a foolish patch

[Andrew Thompson]

On Thu, Feb 19, 2009 at 05:41:07AM +0200, Giorgos Keramidas wrote:
> On Thu, 19 Feb 2009 11:49:02 +0900, Daichi GOTO <daichi at ongs.co.jp> wrote:
> > Hi usb2 folks, first please give me a time to say congratulations! I'm
> > very glad that usb2 is default usb stack right now :)
> >
> > Well but, bad news I have.
> >
> > I have known that usb2 stack have a issue around boot from usb
> > devices. System has been engaging root filesystem mount treatment
> > before completion of device proving in kernel main thread. It leads
> > root mount fail, then system boot fails from usb device.
> >
> > So I have made a patch included. That patch sleeps 30 seconds before
> > root mount treatment while a kernel thread doing usb2 device probing.
> >
> > Yes you know, very foolish patch but I have no idea to fix it in other
> > way. If you have better ideas, please try and commit that.
> 
> Delaying *all* boots for such a long time doesn't seem very good.
> 
> It may be a good idea to patch usb2 to install a SYSINIT handler with
> SI_SUB_CONFIGURE, so that it gets a chance to hook itself at the end of
> the device configuration.  I'll try to do this, unless Hans beats me to
> it of course :)

There has already been a thread about this on usb@, maybe have a read
first.
http://lists.freebsd.org/pipermail/freebsd-usb/2009-February/006242.html

Andrew