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RE: [lwip-users] netif->flags


From: Bill Auerbach
Subject: RE: [lwip-users] netif->flags
Date: Mon, 18 May 2009 17:34:41 -0400

But note that netif_set_link_up does more than set flags - it does stuff for
ARP and IGMP.  I think this has come up before - or something similar - did
you search this mailing list archive for more on this?

Bill

>-----Original Message-----
>From: address@hidden
>[mailto:address@hidden On
>Behalf Of John Kennedy
>Sent: Monday, May 18, 2009 5:22 PM
>To: Mailing list for lwIP users
>Subject: RE: [lwip-users] netif->flags
>
>Jeff,
>That makes sense to me, I was just a little puzzled by why Lwip doesn't
>set NETIF_FLAG_UP with the rest of the flags in low_level_init and why
>there is no comment or anything else I can find that indicates that it
>even needs to be set.  Hence my original question.
>
>-----Original Message-----
>From: Jeff Barber [mailto:address@hidden
>Sent: Monday, May 18, 2009 2:24 PM
>To: Mailing list for lwIP users
>Subject: Re: [lwip-users] netif->flags
>
>(I'm still a newbie with lwIP and am still working on a driver so I
>have no direct experience yet but...)
>
>There are two different state bits that are orthogonal: NETIF_FLAG_UP
>and NETIF_FLAG_LINK_UP.  It appears to me that these are intended to
>reflect, respectively, whether the device driver is "running" and
>whether the device has established a communication link with a peer
>device.  So shouldn't you just unconditionally call netif_set_up once
>at the beginning (assuming your init function succeeded)?  It's what
>I've been planning to do.  I will also have a static IP but I will
>consider my device "up" even if there is no link.  There are separate
>netif_set_link_up and netif_set_link_down calls that allow the driver
>to reflect the current link state.
>
>Think of the way an ethernet interface works on linux (or any other
>unix).  You run "ifconfig eth0 up [...]" administratively to load the
>driver, initialize the device instance, allocate descriptor rings and
>receive buffers and so forth.  This all works even if there's no cable
>plugged into the port.  Then when the cable is plugged in, the driver
>calls "set_link_up" and communication can then take place.  But the
>interface itself does not go up or down every time the link goes up or
>down.  The interface only goes down if I type "ifconfig eth0 down".
>
>Jeff
>
>
>On Mon, May 18, 2009 at 3:36 PM, John Kennedy
><address@hidden> wrote:
>> Please forgive my ignorance.  I think you're right (since I'm not
>using DHCP).  So it sounds like I should have some kind of link checking
>in my code and call netif_set_up and _down as you suggest?  Where/how is
>this type of checking typically done, I presume I will have to poll the
>PHY periodically?
>>
>> John
>>
>> -----Original Message-----
>> From: Bill Auerbach [mailto:address@hidden
>> Sent: Monday, May 18, 2009 1:07 PM
>> To: 'Mailing list for lwIP users'
>> Subject: RE: [lwip-users] netif->flags
>>
>> Does it make sense to call netif_set_up and _down as you see the
>physical link come and go.  With a static IP, as long as there is a
>link, aren't you "up"?
>>
>> Bill
>>
>>>-----Original Message-----
>>>From: address@hidden
>>>[mailto:address@hidden On
>>>Behalf Of John Kennedy
>>>Sent: Monday, May 18, 2009 2:50 PM
>>>To: Mailing list for lwIP users
>>>Subject: RE: [lwip-users] netif->flags
>>>
>>>Yes, but as far as I can tell netif_set_up is only called in autoip.c
>>>and dhcp.c, and I'm not using either yet...
>>>
>>>
>>>
>>>________________________________________
>>>John Kennedy
>>>
>>>
>>>Idaho Technology Inc.
>>>390 Wakara Way
>>>Salt Lake City, UT 84108, USA
>>>
>>>USA: 1-800-735-6544
>>>Bus:+1 (801)736-6354 x448
>>>Fax:+1 (801)588-0507
>>>
>>>http://www.idahotech.com/
>>>-----Original Message-----
>>>From: Simon Goldschmidt [mailto:address@hidden
>>>Sent: Monday, May 18, 2009 8:08 AM
>>>To: Mailing list for lwIP users
>>>Subject: Re: [lwip-users] netif->flags
>>>
>>>
>>>> Hi,
>>>> I'm using lwIP and the socket IF.  The lwIP 1.3.0 source file
>>>ethernetif.c
>>>> contains a function low_level_init which initializes some of the
>netif
>>>> flags; but it does not initialize the flag NETIF_FLAG_UP.  I can't
>>>find
>>>> anywhere else in the code where this flag is set.  Should this flag
>>>> (NETIF_FLAG_UP) be set in low_level_init with the other flags, if
>not
>>>where should this
>>>> flag be set?
>>>
>>>void netif_set_up(struct netif *netif)
>>>--
>>>Neu: GMX FreeDSL Komplettanschluss mit DSL 6.000 Flatrate +
>>>Telefonanschluss für nur 17,95 Euro/mtl.!*
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>>>
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>>
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