On Fri, 2012-06-29 at 02:36 +0000, Arvid Brodin wrote:

Hi,

After 'ip link set eth0 up' on an avr32 board (network driver macb), the device ends up in
operational mode "UNKNOWN":

# ip link
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
    link/ether 00:24:74:00:17:9d brd ff:ff:ff:ff:ff:ff

Unplugging and plugging in the network cable gets the device to mode "UP".

This is a problem for me because I'm trying to use this device as a "slave" device (for a
virtual HSR device*) and I need to be able to decide if the slave device is operational or
not.

Following Stephen's advice here:
http://kerneltrap.org/mailarchive/linux-netdev/2008/9/24/3398834 I checked the macb.c code
and noticed they do not call netif_carrier_off() neither before register_netdev() nor in
dev_open().

It should be called after register_netdev() and before the driver's
ndo_open implementation returns.

I added the call before register_netdev(), which fixed the problem. However, if I then
enable IPv6:

# ip link set eth0 up
ADDRCONF(NETDEV_UP): eth0: link is not ready
eth0: link up (100/Full)
ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready

This looks normal.

Any idea what is happening / what I'm doing wrong? (This is not just cosmetic; is some
situations this seems to kill the interface - e.g. ping does not work, down/up does not
help...) Things work fine without IPv6 configured.

Perhaps some packets sent automatically by IPv6 are triggering a driver
bug?  Or there is a bug in multicast support, which IPv6 always uses.

Ben.

*N.B. I'm writing a driver for a network protocol called "High-availability Seamless
Redundancy".

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.