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Date: Thu, 1 Sep 2011 07:46:16 +0200 From: Jiri Pirko <jpirko@...hat.com> To: Stephen Hemminger <shemminger@...tta.com> Cc: Ben Hutchings <bhutchings@...arflare.com>, Ben Greear <greearb@...delatech.com>, Nicolas de Pesloüan <nicolas.2p.debian@...il.com>, Michał Mirosław <mirqus@...il.com>, netdev@...r.kernel.org, davem@...emloft.net, eric.dumazet@...il.com Subject: Re: [patch net-next-2.6 1/2] net: allow to change carrier via sysfs Wed, Aug 31, 2011 at 11:40:23PM CEST, shemminger@...tta.com wrote: >On Wed, 31 Aug 2011 22:36:45 +0100 >Ben Hutchings <bhutchings@...arflare.com> wrote: > >> On Wed, 2011-08-31 at 13:48 -0700, Ben Greear wrote: >> > On 08/31/2011 01:31 PM, Nicolas de Pesloüan wrote: >> > > Le 31/08/2011 22:12, Ben Hutchings a écrit : >> > >> On Wed, 2011-08-31 at 22:03 +0200, Nicolas de Pesloüan wrote: >> > >>> Le 31/08/2011 10:45, Jiri Pirko a écrit : >> > >>> >> > >>>>>>> Do you expect drivers using implementation different than just calling >> > >>>>>>> netif_carrier_on/off? Or is it supposed to also e.g. power down PHYs? >> > >>>>>> Yes, generally it can be used also for en/disable phy, for testing >> > >>>>>> purposes if hw and driver would support it. >> > >>>>> >> > >>>>> I'd like to see this working for GRE tunnel devices (for keepalive >> > >>>>> daemon to be able to indicate to routing daemons whether tunnel is >> > >>>>> really working) - implementation would be identical to dummy's case. >> > >>>>> Should I prepare a patch or can I leave it to you? >> > >>>> >> > >>>> Ok, I can include it to this patchset (I'm going to repost first patch >> > >>>> anyway) >> > >>> >> > >>> Can't we assume that the dummy's case is the default behavior and >> > >>> register this default >> > >>> ndo_change_carrier callback for every device ? >> > >> >> > >> You have got to be joking. No device driver that has real link >> > >> monitoring should use this implementation. >> > > >> > > Well, why not? Arguably, this is probably not the feature one would use every day, but... >> > > >> > > Testing a cluster reaction to a link down event would be easier if one doesn't need to unplug the cable for the test. I understand that one can turn off the >> > > switch port (physical or virtual), but echo 0 > /sys/class/net/eth0/carrier would be nice too. >> > >> > There is special hardware out there that can do bypass, and often it also has a mode >> > that will programatically cut link by throwing some relays. We use this for our >> > testing equipment... >> > >> > If there is some way to twiddle standard-ish hardware to actually drop link, that >> > would be neat. I'd think it should be an ethtool type of thing, however. >> >> We need to be able to control this as part of our driver test suite (on >> the peer, not the device under test). There are various MDIO bits that >> look like they should do this but unfortunately they don't have >> consistent effects. Besides that, many PHYs are not MDIO-manageable. >> So this would have to be a device-specific operation, whether it's >> exposed through ethtool or sysfs. >> >> > Actually dropping link, and letting that naturally propagate up the stack seems >> > more reasonable than lying about the status half way up the stack. >> > >For testing clustering, there are hooks in vmware and QEMU/KVM to allow >dropping carrier on the VM side. Afaik in kvm this is only possible on emulated e1000 (last time I checked). -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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