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Date: Mon, 23 May 2011 10:14:05 -0700
From: Randy Dunlap <rdunlap@xenotime.net>
To: Micha Nelissen <micha@neli.hopto.org>, lud <linux-usb@vger.kernel.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: USB stick as root device does not work
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[adding cc: of linux-usb mailing list]

On Sun, 22 May 2011 16:13:17 +0200 Micha Nelissen wrote:

> Hi,
> 
> Using USB stick as root device does not work for me. I specify
> 'root=/dev/sdb1 rootwait' on the kernel commandline, but the kernel does
> not wait for the USB stick to be scanned and its partitions found. I
> have a harddisk which is /dev/sda, and this USB stick would be /dev/sdb.
> 
> I think blk_lookup_devt returns the block device number even if it does
> not exist yet, and init/do_mounts.c:473 therefore skips waiting:
> 
>         if ((ROOT_DEV == 0) && root_wait) {
> 
> due to ROOT_DEV having become non-zero already.
> 
> If I use the commandline: 'root=/dev/sdb1 rootdelay=5' then it does
> mount and boot properly. However, using rootwait seems safer and faster
> to me, that it's meant for this use case.
> 
> Thanks for any pointers,
> 
> Micha
> --

---
~Randy
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