From mboxrd@z Thu Jan 1 00:00:00 1970 From: Harald Hoyer Subject: Re: [PATCH net-next] sysfs: add entry to indicate network interfaces with random MAC address Date: Wed, 21 Jul 2010 08:47:36 +0200 Message-ID: <4C469808.5060308@redhat.com> References: <20100720141816.16f0a939@nehalam> <20100720.142045.32697196.davem@davemloft.net> <4C469313.6010807@redhat.com> <20100720.233457.267367495.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: shemminger@vyatta.com, bhutchings@solarflare.com, sassmann@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, gospo@redhat.com, gregory.v.rose@intel.com, alexander.h.duyck@intel.com, leedom@chelsio.com To: David Miller Return-path: In-Reply-To: <20100720.233457.267367495.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 07/21/2010 08:34 AM, David Miller wrote: > From: Harald Hoyer > Date: Wed, 21 Jul 2010 08:26:27 +0200 > >> On 07/20/2010 11:20 PM, David Miller wrote: >>> From: Stephen Hemminger >>> Date: Tue, 20 Jul 2010 14:18:16 -0700 >>> >>>> No one mentioned that the first octet of an Ethernet address already >>>> indicates "software generated" Ethernet address. Per the standard, >>>> if bit 1 is set it means address is locally assigned. >>>> >>>> static inline bool is_locally_assigned_ether(const u8 *addr) >>>> { >>>> return (addr[0]& 0x2) != 0; >>>> } >>> >>> W00t! >>> >>> Indeed, can udev just use that? :-) >> >> It already does: >> see /lib/udev/rules.d/75-persistent-net-generator.rules > > So... why doesn't this work? It works.. but the information, that the MAC is randomly generated would be valuable. So, for the non-random locally assigned MAC (with bit 1), we could easily make persistent rules based on the MAC, instead of completely ignoring them, like we do currently.