Re: [PATCH v2 net-next] sky2: use random address if EEPROM is bad
From: Stephen Hemminger <stephen@networkplumber.org>
Date: 2015-08-12 15:28:23
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On Wed, 12 Aug 2015 10:30:05 +0100 Liviu Dudau [off-list ref] wrote:
On Tue, Aug 11, 2015 at 06:01:32PM +0100, Stephen Hemminger wrote:quoted
On Tue, 11 Aug 2015 15:35:56 +0100 Liviu Dudau [off-list ref] wrote:quoted
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.Dudau@arm.com> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org> [Changed handcoded setup to use eth_hw_addr_random() instead] Signed-off-by: Liviu Dudau <Liviu.Dudau@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.