Bug 683527

Summary: Unable to start netconsole on xen domU
Product: Red Hat Enterprise Linux 5 Reporter: Shad L. Lords <slords>
Component: kernel-xenAssignee: Xen Maintainance List <xen-maint>
Status: CLOSED WONTFIX QA Contact: Virtualization Bugs <virt-bugs>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 5.5.zCC: drjones, jzheng, leiwang, lersek, pbonzini, qwan, xen-maint, yuzhang, yuzhou
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-05-17 13:05:38 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
"Add xen pv netconsole support [orabug 6993043] [bz 7258]" none

Description Shad L. Lords 2011-03-09 16:20:24 UTC 
Description of problem:

When trying to setup netconsole on a domU the modprobe fails because the network interface doesn't support pulling.

Version-Release number of selected component (if applicable):

2.6.18-194.26.1

How reproducible:

always

Steps to Reproduce:
1. configure /etc/sysconfig/netconsole
2. service netconsole start
3. observe dmesg and /var/log/messages
  
Actual results:

kernel: netconsole: eth0 doesn't support polling, aborting.

Expected results:

netconsole starts and sends logs to remote host.

Additional info:

It appears that oracle has patched their kernel to support this.  Reference is orabug 6993043
Comment 1 Laszlo Ersek 2011-05-16 14:55:57 UTC 
Created attachment 499178 [details]
"Add xen pv netconsole support  [orabug 6993043] [bz 7258]"

"linux-2.6.18-xen-netconsole-el5u6.patch" from
http://oss.oracle.com/el5/SRPMS-updates/kernel-2.6.18-238.0.0.0.1.el5.src.rpm
Comment 2 Laszlo Ersek 2011-05-17 13:05:38 UTC 
I applied the patch and tried to test it. Unfortunately, it doesn't seem to work at all from the PV domU to a separate physical machine, even though I got netconsole working from dom0 to the same different physical machine. I flushed the entire iptables config in dom0 (policies are ACCEPT), tried with virtual and then shared physical device. netconsole does start in domU, but there's still no traffic due to the domU kernel messages.

I can send UDP packets from the domU to the remote syslog server (my laptop) just fine. I verified the target MAC address on these packets with tcpdump, within the domU, and it does match the netconsole target MAC setting. So, either this patch doesn't work, or I don't know how to set up netconsole in a PV domU.

I can't find any Oracle bug tracker that would return anything useful when I enter "6993043" or "7258". I hunted these together from mailing lists, and I even had to extract the patch from an src rpm (see comment 1). Thus not much justification for the patch is available to me.

This is the smaller problem. The bigger problem is, as I realize now, Paolo has already seen this patch (squashed together with another Oracle patch) and judged it wrong. See bug 605711 comment 0 (note the "[bz 7258]" substring), bug 605711 comment 7, and attachment 425157 [details].

Considering this patch doesn't seem to help where it should, violates written guidelines, and was not submitted to / reviewed by upstream, I'm closing this bug as WONTFIX.