netdev - Re: [PATCH] igbvf: avoid name clash between PF and VF

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Message-ID: <AANLkTin08wA8a5nCnq-djQnTSq1g2TQ7GqYfCEBCTn9l@mail.gmail.com>
Date:	Wed, 30 Jun 2010 13:11:33 +0200
From:	Kay Sievers <kay.sievers@...y.org>
To:	Stefan Assmann <sassmann@...hat.com>
Cc:	Ben Hutchings <bhutchings@...arflare.com>,
	netdev <netdev@...r.kernel.org>,
	e1000-devel@...ts.sourceforge.net,
	"Duyck, Alexander H" <alexander.h.duyck@...el.com>,
	gregory.v.rose@...el.com, jeffrey.t.kirsher@...el.com,
	Andy Gospodarek <gospo@...hat.com>, harald@...hat.com
Subject: Re: [PATCH] igbvf: avoid name clash between PF and VF

On Wed, Jun 30, 2010 at 12:57, Stefan Assmann <sassmann@...hat.com> wrote:
> On 30.06.2010 12:44, Ben Hutchings wrote:
>> On Wed, 2010-06-30 at 10:53 +0200, Stefan Assmann wrote:
>>> From: Stefan Assmann <sassmann@...hat.com>
>>>
>>> It looks like the VFs get initialized before all the PFs are. Therefore
>>> the udev mapping MAC <-> ethX (for PFs) gets screwed because the VFs
>>> may grab the ethX interface names (reserved by udev) for the PFs.
>>>
>>> Example:
>>> igb max_vfs=0
>>> eth0      Link encap:Ethernet  HWaddr 00:13:20:F7:A5:9E
>>> eth1      Link encap:Ethernet  HWaddr 00:13:20:F7:A5:9F
>>> eth2      Link encap:Ethernet  HWaddr 00:13:20:F7:A5:A0
>>> eth3      Link encap:Ethernet  HWaddr 00:13:20:F7:A5:A1
>>> igb max_vfs=1
>>> eth0      Link encap:Ethernet  HWaddr 00:13:20:F7:A5:9E
>>> eth1      Link encap:Ethernet  HWaddr 0A:CF:41:69:F7:A9
>>> eth2      Link encap:Ethernet  HWaddr 3A:FE:20:4C:2A:3B
>>> eth3      Link encap:Ethernet  HWaddr C6:C3:B1:56:C9:A4
>>> eth3_rename Link encap:Ethernet  HWaddr 00:13:20:F7:A5:9F
>>> eth4      Link encap:Ethernet  HWaddr 6E:8A:8A:A3:5F:69
>>> eth4_rename Link encap:Ethernet  HWaddr 00:13:20:F7:A5:A0
>>> eth5_rename Link encap:Ethernet  HWaddr 00:13:20:F7:A5:A1
>>>
>>> In the example above VF 0A:CF:41:69:F7:A9 grabs eth1 but udev
>>> has a rule that says eth1 should be assigned PF 00:13:20:F7:A5:9F
>>> (eth3_rename) and waits for the VF to disappear to rename eth3_rename
>>> to eth1. Unfortunately eth1 is not going to disappear.
>>> This is not a udev bug since udev doesn't create persistent rules for
>>> VFs as their MAC address changes every reboot.
>> [...]
>>
>> I think it is a bug in the udev rules: udev should rename the VFs even
>> though their names won't be persistent.

Udev writes out these configs to a rules file, and therefore can never
handle random MAC addresses, as they would just accumulate in the
rules file with a new entry at every bootup.

Stuff like this is just not supported at the moment with the rather
simple logic it has, and there is no current plan/idea, or anybody
working on changing/improving this at the moment.

Kay
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