On Wed, Aug 12, 2015 at 04:28:23PM +0100, Stephen Hemminger wrote:
> On Wed, 12 Aug 2015 10:30:05 +0100
> Liviu Dudau <liviu.du...@arm.com> wrote:
>
> > On Tue, Aug 11, 2015 at 06:01:32PM +0100, Stephen Hemminger wrote:
> > > On Tue, 11 Aug 2015 15:35:56 +0100
> > > Liviu Dudau <liviu.du...@arm.com> wrote:
> > >
> > > > On some embedded systems the EEPROM does not contain a valid MAC
> > > > address.
> > > > In that case it is better to fallback to a generated mac address and
> > > > let init scripts fix the value later.
> > > >
> > > > Reported-by: Liviu Dudau <liviu.du...@arm.com>
> > > > Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
> > > > [Changed handcoded setup to use eth_hw_addr_random() instead]
> > > > Signed-off-by: Liviu Dudau <liviu.du...@arm.com>
> > > > ---
> > > > I have tested this on my Juno platform and I can successfully do an
> > > > nfsroot boot.
> > > >
> > > > Best regards,
> > > > Liviu
> > > >
> > > > drivers/net/ethernet/marvell/sky2.c | 7 +++++++
> > > > 1 file changed, 7 insertions(+)
> > > >
> > > > diff --git a/drivers/net/ethernet/marvell/sky2.c
> > > > b/drivers/net/ethernet/marvell/sky2.c
> > > > index d9f4498..c309879 100644
> > > > --- a/drivers/net/ethernet/marvell/sky2.c
> > > > +++ b/drivers/net/ethernet/marvell/sky2.c
> > > > @@ -4819,6 +4819,13 @@ static struct net_device
> > > > *sky2_init_netdev(struct sky2_hw *hw, unsigned port,
> > > > memcpy_fromio(dev->dev_addr, hw->regs + B2_MAC_1 + port
> > > > * 8,
> > > > ETH_ALEN);
> > > >
> > > > + /* if the address is invalid, use a random value */
> > > > + if (!is_valid_ether_addr(dev->dev_addr)) {
> > > > + netdev_warn(dev,
> > > > + "Invalid MAC address, defaulting to random\n");
> > > > + eth_hw_addr_random(dev);
> > > > + }
> > > > +
> > > > return dev;
> > > > }
> > > >
> > >
> > > This is not enough, you need to program the hardware with the new random
> > > MAC
> > > address. The easiest way is calling sky2_set_mac_address, but you need to
> > > convert
> > > the address from array back to sockaddr.
> > >
> >
> > OK, I am a bit confused as to why sky2_set_mac_address is needed here, as
> > this was not
> > required by the existing function. Given that in my tests I get a random
> > MAC address
> > assigned every time to the device and I can see the same MAC address with
> > ifconfig, how
> > can I test the effect of sky2_set_mac_address if I add it?
>
> The network device address is stored in two places. One is in the
> kernel (dev->dev_addr) and is used by networking stack.
> The other is the hardware (actually two places) and is used filtering
> received packets
> in the PHY and for sending hardware generated pause frames.
>
> When a random address is generated, you need to tell the hardware
> to use that address as well. I suspect your hardware maybe limited in
> functionality
> and not do the normal filtering.
>
I understand now, thanks for explaining it. I admit my tests were very limited
and I did not
try to capture any packets using the interface. I thought the DHCP discovery
requires the
MAC address to be correct in the hardware to work, but it might be that the
kernel's DHCP
client is more thorough than userspace.
I will add the setting of the MAC address in v3.
Best regards,
Liviu
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
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