Messages in this thread | | | Subject | Re: [PATCH net-next] sysfs: add entry to indicate network interfaces with random MAC address | From | Ben Hutchings <> | Date | Tue, 20 Jul 2010 13:07:36 +0100 |
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On Tue, 2010-07-20 at 13:47 +0200, Stefan Assmann wrote: > On 20.07.2010 13:20, Ben Hutchings wrote: > > On Tue, 2010-07-20 at 12:50 +0200, Stefan Assmann wrote: > >> From: Stefan Assmann <sassmann@redhat.com> > >> > >> Reserve a bit in struct net_device to indicate whether an interface > >> generates its MAC address randomly, and expose the information via > >> sysfs. > >> May look like this: > >> /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/net/eth0/ifrndmac > >> > >> By default the value of ifrndmac is 0. Any driver that generates the MAC > >> address randomly should return a value to 1. > > > > The name should incorporate 'address', not 'mac', for consistency with > > the generic 'address' attribute. > > We can call it "ifrndhwaddr" if that's more consistent. > > > > > What about devices that 'steal' MAC addresses from slave devices? > > Currently I believe udev has special cases for them but ideally these > > drivers would indicate explicitly that their addresses are not stable > > identifiers (even though they aren't random). > > It's really up to the driver to decide whether it makes sense to set the > flag or not. The question is what should udev do with these MAC address > stealing devices apart from ignoring them? Sorry I have no higher > insight into it. > This flag has the purpose to allow udev to explicitly handle devices > that generate their MAC address randomly and generate a persistent > rule based on the device path instead of the MAC address. > I'm open for suggestions but I'm not sure we can handle both cases with > a single flag.
OK, then call it something like 'address_temporary'.
> JFYI this is an alternative approach to changing the kernel name of VFs > to vfeth. The advantage of this way should be that we don't break any > user-space applications that rely on network interfaces being names > "ethX". Actually this goes in the direction of "fixing udev" which was > what you asked for in your comment on my first patch concering vfeth. :) > > > > > [...] > >> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > >> index b626289..2ea0298 100644 > >> --- a/include/linux/netdevice.h > >> +++ b/include/linux/netdevice.h > >> @@ -845,6 +845,7 @@ struct net_device { > >> #define NETIF_F_FCOE_MTU (1 << 26) /* Supports max FCoE MTU, 2158 bytes*/ > >> #define NETIF_F_NTUPLE (1 << 27) /* N-tuple filters supported */ > >> #define NETIF_F_RXHASH (1 << 28) /* Receive hashing offload */ > >> +#define NETIF_F_RNDMAC (1 << 29) /* Interface with random MAC address */ > > [...] > > > > This is not really a feature, and we are running out of real feature > > bits. Can you find somewhere else to put this flag? > > Actually Dave Miller suggested to put it there. What other place is > there to put it?
If Dave said that then I'm sure it's OK.
However, if you define this as an interface flag (net_device::flags; <linux/if.h>) and add it to the set of changeable flags in __dev_change_flags(), user-space will be able to clear the flag if it later sets a stable address.
Ben.
-- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.
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