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Date: Wed, 18 Apr 2012 16:13:08 -0600
From: Chris Friesen <chris.friesen@genband.com>
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To: LKML <linux-kernel@vger.kernel.org>, linux-hotplug@vger.kernel.org
Subject: Re: "udevadm info --attribute-walk --path=/block/sda" doesn't show
 parents
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On 04/18/2012 03:42 PM, Chris Friesen wrote:
> 
> I have a 2.6.34.10-based kernel with udev-161 (also tested with udevadm from udev-173).
> 
> When I run "udevadm info --attribute-walk --path=/block/sda" it just shows the device
> itself, and doesn't walk the whole chain showing the parents.
> 
> Is there anything I can do, or am I caught with a kernel that isn't properly supported?
> I'm not subscribed to the hotplug list, so cc'ing me would be appreciated.
> 
> 
> I don't know what's causing the problem, but I find it suspicious that /sys/block/sda
> is a directory rather than a symlink like it is on my 2.6.35.14 laptop.  I'm poking
> around in the udevadm code now.

Looking at the udevadm code led me to the following:

On the problematic 2.6.34 machine:

root@typhoon-base-unit0:/root> ls -l /sys/dev/block/
<snip>
lrwxrwxrwx 1 root root 0 Apr 18 14:34 8:0 -> ../../block/sda



On my 2.6.35 machine:

[cfriesen@blah udev-173]$ ls -l /sys/dev/block/
<snip>
lrwxrwxrwx. 1 root root 0 Apr 18 15:54 8:0 -> ../../devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda



So where do I go from here?  Is there a simple kernel change to make my 2.6.34
kernel behave more like the more recent one?  Would an older version of udev be
able to parse my 2.6.34 /sys directory properly, or do I need to figure out a
way to parse /sys manually?

Thanks,
Chris







-- 
Chris Friesen
Software Developer
GENBAND
chris.friesen@genband.com
www.genband.com