netdev - Re: netconsole fun

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Message-ID: <20121211164526.GB7481@neilslaptop.think-freely.org>
Date:	Tue, 11 Dec 2012 11:45:26 -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 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

> [ 3.840306] tg3.c:v3.127 (November 14, 2012)
> [ 3.873390] tg3 0000:08:00.0 eth0: Tigon3 [partno(BCM95754) rev b002] (PCI Express) MAC address xx:xx:xx:xx:xx:xx
> [ 3.873406] tg3 0000:08:00.0 eth0: attached PHY is 5787 (10/100/1000Base-T Ethernet) (WireSpeed[1], EEE[0])
> [ 3.873413] tg3 0000:08:00.0 eth0: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[0] TSOcap[1]
> [ 3.873424] tg3 0000:08:00.0 eth0: dma_rwctrl[76180000] dma_mask[64-bit]
> ...
> [ 3.884239] 3c59x: Donald Becker and others.
> [ 3.884263] 0000:07:05.0: 3Com PCI 3c905C Tornado at ffffc9000187cf80.
> 
> Regards,
> Peter Hurley
> 
> 
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