netdev - Re: netconsole fun

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Date:	Tue, 11 Dec 2012 16:19:09 -0500
From:	Neil Horman <nhorman@...driver.com>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org
Subject: Re: netconsole fun

On Tue, Dec 11, 2012 at 12:17:52PM -0500, Peter Hurley wrote:
> On Tue, 2012-12-11 at 11:45 -0500, Neil Horman wrote:
> > On Tue, Dec 11, 2012 at 10:16:51AM -0500, Peter Hurley wrote:
> > > On Tue, 2012-12-11 at 09:30 -0500, Neil Horman wrote:
> > > > On Tue, Dec 11, 2012 at 09:19:52AM -0500, Peter Hurley wrote:
> > > > > On Tue, 2012-12-11 at 04:51 +0000, Cong Wang wrote:
> > > > > > On Mon, 10 Dec 2012 at 14:17 GMT, Peter Hurley <peter@...leysoftware.com> wrote:
> > > > > > > Now that netpoll has been disabled for slaved devices, is there a
> > > > > > > recommended method of running netconsole on a machine that has a slaved
> > > > > > > device?
> > > > > > >
> > > > > > 
> > > > > > Yes, running it on the master device instead.
> > > > > 
> > > > > Thanks for the suggestion, but:
> > > > > 
> > > > > [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.7.0-rc8-xeon ...... netconsole=@....168.10.99/br0,30000@....168.10.100/xx:xx:xx:xx:xx:xx
> > > > > ...
> > > > > [ 5.289869] netpoll: netconsole: local port 6665
> > > > > [ 5.289885] netpoll: netconsole: local IP 192.168.10.99
> > > > > [ 5.289892] netpoll: netconsole: interface 'br0'
> > > > > [ 5.289898] netpoll: netconsole: remote port 30000
> > > > > [ 5.289907] netpoll: netconsole: remote IP 192.168.10.100
> > > > > [ 5.289914] netpoll: netconsole: remote ethernet address xx:xx:xx:xx:xx:xx
> > > > > [ 5.289922] netpoll: netconsole: br0 doesn't exist, aborting
> > > > > [ 5.289929] netconsole: cleaning up
> > > > > ...
> > > > > [ 9.392291] Bridge firewalling registered
> > > > > [ 9.396805] device eth1 entered promiscuous mode
> > > > > [ 9.418350] eth1:  setting full-duplex.
> > > > > [ 9.421268] br0: port 1(eth1) entered forwarding state
> > > > > [ 9.423354] br0: port 1(eth1) entered forwarding state
> > > > > 
> > > > > 
> > > > > Is there a way to control or associate network device names prior to
> > > > > udev renaming?
> > > > > 
> > > > That looks like a systemd problem (or more specifically a boot dependency
> > > > problem).  You need to modify your netconsole unit/service file to start after
> > > > all your networking is up.  NetworkManager provides a dummy service file for
> > > > this purpose, called networkmanager-wait-online.service
> > > 
> > > Ok. So with a single physical network interface that will be bridged,
> > > netconsole cannot used for kernel boot messages.
> > > 
> > > With a machine with multiple nics, is there a way to control device
> > > naming so that the interface name to be used by netconsole specified on
> > > the boot command line will actually corresponding to the intended
> > > device. For example,
> > > 
> > > [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.7.0-rc8-xeon ...... netconsole=@....168.1.123/eth0,30000@....168.1.139/xx:xx:xx:xx:xx:xx
> > > ....
> > > [ 4.092184] 3c59x: Donald Becker and others.
> > > [ 4.092204] 0000:07:05.0: 3Com PCI 3c905C Tornado at ffffc9000186cf80.
> > > [ 4.094035] tg3.c:v3.125 (September 26, 2012)
> > > ....
> > > [ 4.125038] tg3 0000:08:00.0 eth1: Tigon3 [partno(BCM95754) rev b002] (PCI Express) MAC address xx:xx:xx:xx:xx:xx
> > > [ 4.125055] tg3 0000:08:00.0 eth1: attached PHY is 5787 (10/100/1000Base-T Ethernet) (WireSpeed[1], EEE[0])
> > > [ 4.125062] tg3 0000:08:00.0 eth1: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[0] TSOcap[1]
> > > [ 4.125068] tg3 0000:08:00.0 eth1: dma_rwctrl[76180000] dma_mask[64-bit]
> > > 
> > > This is attaching netconsole to the wrong device because bus
> > > enumeration, and therefore load order, is not consistent from boot to
> > > boot.
> > > 
> > No, theres no way to do that.  As you note device ennumeration isn't consistent
> > accross boots, thats why udev creates rules to rename devices based on immutable
> > (or semi-immutable) data, like mac addresses, or pci bus locations).  Once that
> > happens, you'll have consistent names for your interfaces, and that work will be
> > guaranteed to be done after networkmanager has finished opening all the
> > interfaces that it needs (hence my suggestion to make netconsole service
> > dependent on networkmanager service startup completing).
> > 
> > Neil
> 
> Thanks for all your help here, Neil. Very much appreciated.
> 
> Happy Holidays,
> Peter Hurley
> 
No problem, anytime!
Happy Holidays
Neil

> 
> 
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