From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [patch iproute2 1/6] iproute2: ipa: show switch id Date: Thu, 4 Dec 2014 19:24:51 +0100 Message-ID: <20141204182451.GI1861@nanopsycho.orion> References: <1417683438-10935-1-git-send-email-jiri@resnulli.us> <1417683438-10935-2-git-send-email-jiri@resnulli.us> <87y4qne6if.fsf@x220.int.ebiederm.org> <20141204163024.GG1861@nanopsycho.orion> <87388v9ua6.fsf@x220.int.ebiederm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, davem@davemloft.net, nhorman@tuxdriver.com, andy@greyhouse.net, tgraf@suug.ch, dborkman@redhat.com, ogerlitz@mellanox.com, jesse@nicira.com, pshelar@nicira.com, azhou@nicira.com, ben@decadent.org.uk, stephen@networkplumber.org, jeffrey.t.kirsher@intel.com, vyasevic@redhat.com, xiyou.wangcong@gmail.com, john.r.fastabend@intel.com, edumazet@google.com, jhs@mojatatu.com, sfeldma@gmail.com, f.fainelli@gmail.com, roopa@cumulusnetworks.com, linville@tuxdriver.com, jasowang@redhat.com, nicolas.dichtel@6wind.com, ryazanov.s.a@gmail.com, buytenh@wantstofly.org, aviadr@mellanox.com, nbd@openwrt.org, alexei.starovoitov@gmail.com, Neil.Jerram@metaswitch.com, ronye@mellanox.com, simon.horman@netronome.com, alexander.h.duyck@redhat.com, john.ronciak@intel.com, mleitner@redhat.com, shrijeet@gmail.com, gospo@cumulusnetworks.com, bcrl@kvack.org, hemal@broadcom.c To: "Eric W. Biederman" Return-path: Received: from mail-wi0-f176.google.com ([209.85.212.176]:49786 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932723AbaLDSYy (ORCPT ); Thu, 4 Dec 2014 13:24:54 -0500 Received: by mail-wi0-f176.google.com with SMTP id ex7so35649242wid.9 for ; Thu, 04 Dec 2014 10:24:53 -0800 (PST) Content-Disposition: inline In-Reply-To: <87388v9ua6.fsf@x220.int.ebiederm.org> Sender: netdev-owner@vger.kernel.org List-ID: Thu, Dec 04, 2014 at 06:52:49PM CET, ebiederm@xmission.com wrote: >Jiri Pirko writes: > >> Thu, Dec 04, 2014 at 05:15:04PM CET, ebiederm@xmission.com wrote: >>>Jiri Pirko writes: >>> >>>Would someone please explain to me what a switch id is? >>> >>>I looked in the kernel source, and I looked here and while I know >>>switches I don't have a clue what a switch id is. >>> >>>My primary concern at this point is that you have introduced a global >>>identifier that is isn't a hardware property (it certainly does not look >>>like a mac address) and that is unique across network namespaces and >>>thus breaks checkpoint/restart (aka CRIU). >> >> IFLA_PHYS_SWITCH_ID is very similar to IFLA_PHYS_PORT_ID. It is >> generated by the driver and ensures that there is the same switch id for >> all ports belonging to the same switch chip/asic. It is up to the driver >> how to implement the id. I would like to point you to driver >> implementing ndo_get_phys_port_id > >Looking at ndo_get_phys_port_id it is just the per port mac address. Or >guid in the case of infiniband. Which really makes me wonder why we >didn't use the same abstractions in the code for address types that we >do for hardware addresses. > >Using mac address or other hardware addresses that are used for layer 2 >addressing makes sense to me. There is a long tradition of that and as >I recall protocols like STP actually requiring having a different mac >address per port. > >When I asked the question I thought the switch id was going to be >something like the ifindex, the software index of a network device. > > >Finally having tracked down the rocker implementation of >rocker_port_switch_parent_id_get I see it you are reading some 64bit >hardware register. > >Which leads me to ask what are the semantics of switch_id? > >Is the switch id an identifier with a prefix from IEEE and assigned by >the manufacture so that it is guaranteed to the tolerances of the >manufacturing process to be globally unique? It is up to the driver what to use. It can use mac addr. This is same as for phys port id. > >Is the switch id a random number that is statistically likely to be >globally unique because you have enough bits? As I recall you need >at least 128 bits to have a reasonable chance of a random number >avoiding the birthday paradox. > >Do we need some kind of manufacturer id to tell one switch id from >another? > >Is the switch id persistent across reboots? Yes it is (as for phys port id). > >>>Also what in the world does PHYS mean in IFLA_PHYS_SWITCH_ID? Does that >>>mean we can't have a purely software implementation of this interface? >>>Given that we will want a software implementation at some point >>>including PHYS in the name seems completely wrong. >> >> We can remove the "PHYS", no problem. I do not understand what you say >> about "software implementation". The point is to allow hw switch/ish >> chips to be supported. > >If we are talking about something typically stored in a eeprom like a >mac address phys seems appropriate. Yes, we are. > >Still having a definition of this switch id clean clear enough that >net/bridge and drivers/net/macvlan can implement it seems important. I don't understand why would net/bridge or driver/net/macvlan want to implement this. The purpose is to group ports/netdevs which are part of the same hw switch. > >Even more important is having a definition of switch id clear enough >that userspace can use the switch id to do something useful. Userspace threats this the same it treats phys port id. if two ports/netdevs has same switch id, they belong under same hw switch. That's all. > >Right now switch id looks like one of those weird one manufacturer >properties that is fine to expose as a driver specific property >but I don't yet see it being a generic property I that can be used >usefully in userspace. > >So can we please get some clear semantics or failing that can we please >not expose this to userspace as generic property. I thought that the semantics is clean. Looks like I will have to update Documentation/networking/switchdev.txt adding some more info about this. > >Thanks, >Eric > > > >>>> Signed-off-by: Jiri Pirko >>>> --- >>>> include/linux/if_link.h | 1 + >>>> ip/ipaddress.c | 8 ++++++++ >>>> 2 files changed, 9 insertions(+) >>>> >>>> diff --git a/include/linux/if_link.h b/include/linux/if_link.h >>>> index 4732063..a6e2594 100644 >>>> --- a/include/linux/if_link.h >>>> +++ b/include/linux/if_link.h >>>> @@ -145,6 +145,7 @@ enum { >>>> IFLA_CARRIER, >>>> IFLA_PHYS_PORT_ID, >>>> IFLA_CARRIER_CHANGES, >>>> + IFLA_PHYS_SWITCH_ID, >>>> __IFLA_MAX >>>> }; >>>> >>>> diff --git a/ip/ipaddress.c b/ip/ipaddress.c >>>> index 4d99324..bd36a07 100644 >>>> --- a/ip/ipaddress.c >>>> +++ b/ip/ipaddress.c >>>> @@ -589,6 +589,14 @@ int print_linkinfo(const struct sockaddr_nl *who, >>>> b1, sizeof(b1))); >>>> } >>>> >>>> + if (tb[IFLA_PHYS_SWITCH_ID]) { >>>> + SPRINT_BUF(b1); >>>> + fprintf(fp, "switchid %s ", >>>> + hexstring_n2a(RTA_DATA(tb[IFLA_PHYS_SWITCH_ID]), >>>> + RTA_PAYLOAD(tb[IFLA_PHYS_SWITCH_ID]), >>>> + b1, sizeof(b1))); >>>> + } >>>> + >>>> if (tb[IFLA_OPERSTATE]) >>>> print_operstate(fp, rta_getattr_u8(tb[IFLA_OPERSTATE]));