netdev - Re: [PATCH] gianfar: Add gfar_change

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Date:   Fri, 7 Dec 2018 14:07:02 +0000
From:   Joakim Tjernlund <Joakim.Tjernlund@...inera.com>
To:     "andrew@...n.ch" <andrew@...n.ch>
CC:     "claudiu.manoil@....com" <claudiu.manoil@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] gianfar: Add gfar_change_carrier()

On Thu, 2018-12-06 at 20:43 +0100, Andrew Lunn wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> 
> 
> > I can have a look at using dormant, but what is change_carrier
> > supposed to do if not this?
> 
> It is intended for interfaces which are stacked, like the team driver,
> and for devices which don't have a phy, e.g. tun, and dummy.
> 
> > I didn't find a tool for DORMANT, I guess i will have to write one
> > myself(using SIOCGIFFLAGS, SIOCSIFFLAGS)?
> 
> ip link should be able to set it.
> 
> Try ip link set mode dormant dev eth0
> 
>     Andrew

Been a bit busy today but now I have played with dormant using ip link and got some odd results:
# > ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.20.0.246  netmask 255.255.0.0  broadcast 172.20.255.255
        inet6 fe80::ad9c:b230:1da8:1821  prefixlen 64  scopeid 0x20<link>
        ether 8c:16:45:89:cf:c6  txqueuelen 1000  (Ethernet)
        RX packets 1848903  bytes 736764445 (702.6 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 627462  bytes 222453345 (212.1 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16  memory 0xdc200000-dc220000  
# > ip link set mode dormant dev eth0
 ping sunet.se
PING sunet.se (192.36.171.231) 56(84) bytes of data.
64 bytes from webc.sunet.se (192.36.171.231): icmp_seq=1 ttl=54 time=2.22 ms
64 bytes from webc.sunet.se (192.36.171.231): icmp_seq=2 ttl=54 time=2.17 ms

# > ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.20.0.246  netmask 255.255.0.0  broadcast 172.20.255.255
        inet6 fe80::ad9c:b230:1da8:1821  prefixlen 64  scopeid 0x20<link>
        ether 8c:16:45:89:cf:c6  txqueuelen 1000  (Ethernet)
        RX packets 1905479  bytes 753549572 (718.6 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 648266  bytes 224421617 (214.0 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16  memory 0xdc200000-dc220000  
still RUNNING ..

#> ip link show eth0
5: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DORMANT group default qlen 

state is still UP ?

# > ip link set state dormant dev eth0
# > ip link show eth0
5: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state DORMANT mode DORMANT group default qlen 1000
# > ifconfig eth0
eth0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
...

Now both state and not RUNNING :)
but ...
 # ping sunet.se
PING sunet.se (192.36.171.231) 56(84) bytes of data.
64 bytes from webc.sunet.se (192.36.171.231): icmp_seq=1 ttl=54 time=2.43 ms
64 bytes from webc.sunet.se (192.36.171.231): icmp_seq=2 ttl=54 time=2.31 ms

I can still ping though. Is this how it is supposed to work ? No sure how state and mode relate to each other either.

 Jocke