Red Hat Bugzilla – Bug 770593
udev failing to substitute $tempnode for USB devices
Last modified: 2013-02-13 19:00:41 EST
Created attachment 549734 [details]
udev rules file to demonstrate the problem
Description of problem:
With a udev rule for a USB device with an ADD/RUN rule, plugging in the device triggers the rule, but the $tempnode substitution is an empty string rather than the correct USB node.
Version-Release number of selected component (if applicable):
How reproducible: 100%
Steps to Reproduce:
1. Install the attached 99-bug.rules file in /etc/udev/rules.d, changing the values for idVendor and idProduct to match a USB device you can use for testing. This script has an echo command for debugging; normally the RUN would be for a more useful program such as fxload.
2. Enable debugging output to syslog: "udevadm control --log-priority=debug"
3. Plug in the device
In syslog, the echo command is shown, but the $tempnode substitution is empty. See the attached file udev-syslog.txt for an example.
The $tempnode substitution should be for a proper USB node, rather than empty.
This worked properly for me in Fedora 14. However, a search did reveal that Terry Barnaby apparently had this problem with Fedora 14:
I am trying to use the same product as Terry, a Xilinx "Platform Cable USB", to program FPGAs, but the problem does not seem to be specific to Xilinx.
Created attachment 549735 [details]
syslog output showing empty $tempnode substitution
Created attachment 549736 [details]
excerpt of output from "udevadm info -e"
Note that this was on a fresh install of Fedora 16, not an upgrade.
This rule matches on the 'device' and the 'interface'. It runs for at least
2 devices at the same time. Youn need to limit that, only the 'usb_device'
has a device node, not the 'usb_interface'
Thanks for the suggestion, Kay. Unfortunately I don't understand udev well enough to know how to solve it.
I only have one device with the vendor and device ID given, so I don't see how it "runs for at least 2 devices at the same time". This worked perfectly on Fedora 14, so I don't understand why it won't work on Fedora 16.
If you could offer a more specific suggestion as to how the rule should be correctly written to avoid the problem you describe, I would greatly appreciate it!
I think the rule should contain:
Any progress on this Bug? I am having the same problem with a Diligent FPGA-USB cable.
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