Messages in this thread | | | Date | Tue, 20 Jul 2010 14:18:16 -0700 | From | Stephen Hemminger <> | Subject | Re: [PATCH net-next] sysfs: add entry to indicate network interfaces with random MAC address |
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On Tue, 20 Jul 2010 13:17:48 -0700 (PDT) David Miller <davem@davemloft.net> wrote:
> From: Ben Hutchings <bhutchings@solarflare.com> > Date: Tue, 20 Jul 2010 15:29:54 +0100 > > > On Tue, 2010-07-20 at 14:41 +0200, Stefan Assmann wrote: > >> Btw, the driver itself could also alter the flag. Then we'd have a well > >> defined way of setting a stable address. > > > > The driver can't know whether an address assigned by the user is stable. > > If userspace can somehow obtain a persistent address, it can kick > udev too. > > I really don't see any real value provided by letting userspace mess > with this. Because the permanence communicated in this value is from > the perspective of the kernel driver, it's really therefore about the > thing that's in ->perm_addr[] not what happens to be in ->addr[] right > now.
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; }
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