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

[Giorgos Keramidas]

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 :)