From: Greg KH <gregkh@linuxfoundation.org>
To: linux-hotplug@vger.kernel.org
Subject: Re: How to determine which device crashes udev in boot?
Date: Mon, 14 Mar 2016 17:49:01 +0000 [thread overview]
Message-ID: <20160314174901.GA27275@kroah.com> (raw)
In-Reply-To: <CAD4SBxADbDuHn45WNxqdcRfFM=uu8=vXUYLhKc6JNaY5JL-DLw@mail.gmail.com>
On Mon, Mar 14, 2016 at 01:48:39PM +0900, iwillallways forget1 wrote:
> I'm trying to narrow which device in an NEC VF-6 causes Linux boots to
> hang, permanently, in udevadm trigger and udevadm settle. Many Google
> searches found many pages but no tutorials on how to debug udev this
> way.
>
> I downloaded fresh copies of Porteus 3.1 32-bit and 64-bit.
What kernel versions are these?
> Porteus 3.1 64-bit boots fine, udev finds everything, x Windows works
> (I told you Windows rulez), etc. Even on this NEC VF-6.
>
> Porteus 3.1 32-bit boots fine on everything except this NEC VF-6, x
> Windows works, etc.
>
> Porteus 3.1 32-bit hangs when starting udev on this NEC VF-6. It's
> not a 120-second timeout in udevadm settle. It never wakes up. The
> Caps Lock key stops toggling the Caps Lock light. The Num Lock key
> stops toggling the Num Lock light. Ctrl+Alt+Delete is ignored. It
> does not appear to be a kernel panic because two of the keyboard
> lights don't flash. It is hanged, frozen, dead.
>
> Booting with "3 nohotplug" works (3 tells Porteus what run level to
> use, and nohotplug is observed by both the kernel and Porteus). In
> text mode I can do some amount of experiments. I don't know how to do
> meaningful experiments, to try to track down which device causes the
> hang.
Try looking at the documentation of udevadm, you can manually enable the
'coldplug' options there to narrow down what hardware is causing the
problem. Odds are, you have a kernel driver that doesn't like the
hardware and it is getting loaded automatically by udev.
good luck!
greg k-h
prev parent reply other threads:[~2016-03-14 17:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-14 4:48 How to determine which device crashes udev in boot? iwillallways forget1
2016-03-14 17:49 ` Greg KH [this message]
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