Date: Sun, 19 Sep 2004 10:30:35 -0700
From: Greg KH <greg@kroah.com>
To: "Alexander E. Patrakov" <patrakov@ums.usu.ru>
Cc: linux-kernel@vger.kernel.org
Subject: Re: udev is too slow creating devices
Message-ID: <20040919173035.GA2345@kroah.com>
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On Sun, Sep 19, 2004 at 10:00:52PM +0600, Alexander E. Patrakov wrote:
> 
> OK. The fact is that, when mounting the root filesystem, the kernel can 
> (?) definitely say "there is no such device, and it's useless to wait 
> for it--so I panic". Is it possible to duplicate this logic in the case 
> with udev and modprobe? If so, it should be built into a common place 
> (either the kernel or into modprobe), but not into all apps.

No, we need to just change the kernel to sit and spin for a while if the
root partition is not found.  This is the main problem right now for
booting off of a USB device (or any other "slow" to discover device.)
It's a known kernel issue, and there are patches for 2.4 for this, but
no one has taken the time to update them for 2.6.

> Then the "char-major" aliases were always broken, do I understand 
> correctly?

Yes, for most drivers they are broken.  Like sound, usb, and others.

> Once we realize that, isn't it the time to mark the 
> "Automatic kernel module loading" in the kernel configuration as BROKEN 
> or OBSOLETE?

Fine with me, I've been wanting to do that for years.  Are you willing
to handle the fallout of such a patch though?  :)

> >With hotplug/udev you *know* that the device node is available when your
> >script in dev.d is called with the appropriate environment variables.
> 
> Yes. Now we have a lot of short scriptlets under /etc/dev.d. But I don't 
> yet see how these scriptlets interact with each other.

What do you mean?  What kind of relationship do you need explained about
them?

thanks,

greg k-h
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