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Date: Fri, 31 Dec 2004 06:58:20 -0200
From: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
To: Paulo Marques <pmarques@grupopie.com>
Cc: Andrew Morton <akpm@osdl.org>, William Park <opengeometry@yahoo.ca>,
       juhl-lkml@dif.dk, linux-kernel@vger.kernel.org
Subject: Re: waiting 10s before mounting root filesystem?
Message-ID: <20041231085820.GA10834@logos.cnet>
References: <20041227195645.GA2282@node1.opengeometry.net> <20041227201015.GB18911@sweep.bur.st> <41D07D56.7020702@netshadow.at> <20041229005922.GA2520@node1.opengeometry.net> <20041230152531.GB5058@logos.cnet> <Pine.LNX.4.61.0412310011400.3494@dragon.hygekrogen.localhost> <Pine.LNX.4.61.0412310234040.4725@dragon.hygekrogen.localhost> <20041231035834.GA2421@node1.opengeometry.net> <20041231014905.30b05a11.akpm@osdl.org> <41D5376A.8000705@grupopie.com>
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On Fri, Dec 31, 2004 at 11:26:34AM +0000, Paulo Marques wrote:
> Andrew Morton wrote:
> >William Park <opengeometry@yahoo.ca> wrote:
> >
> >>-		printk("VFS: Cannot open root device \"%s\" or %s\n",
> >>-				root_device_name, b);
> >>-		printk("Please append a correct \"root=\" boot option\n");
> >>+		if (--tryagain) {
> >>+		    printk (KERN_WARNING "VFS: Waiting %dsec for root 
> >>device...\n", tryagain);
> >>+		    ssleep (1);
> >>+		    goto retry;
> >>+		}
> >>+		printk (KERN_CRIT "VFS: Cannot open root device \"%s\" or 
> >>%s\n", root_device_name, b);
> >>+		printk (KERN_CRIT "Please append a correct \"root=\" boot 
> >>option\n");
> >
> >
> >Why is this patch needed?  If it is to offer the user a chance to insert
> >the correct medium or to connect the correct device, why not rely upon the
> >user doing that thing and then hitting reset?
> 
> No, no. The problem is not user interaction.
> 
> The problem is that the USB subsystem takes a lot of time to go through 
> the hostcontrollers -> hubs -> devices. By the time it finds the USB 
> mass storage that is supposed to be used as root filesystem, the kernel 
> had already panic'ed.
> 
> IMHO the kernel should handle this case just fine, without the need for 
> initrd's. After all the user says "my root filesystem is /dev/sda1", and 
> the kernel panic's even though the filesystem is there. This doesn't 
> seem like a correct bahavior.

Well, Paulo's has more of a clue than I do. 

Some CD drives suffer from the same issues.