RE: [lwip-users] netif->flags

[John Kennedy]

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
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>>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 +
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