dev->hard_header ?

dev->hard_header ?

[Seong Moon]

In Layer 3 Protocols(eg. IP, IPv6, ...),
they calls dev_queue_xmit() to send their data.

Before calling dev_queue_xmit(),
does the layer 3 protocols always call dev->hard_header ?

Actually, I'm not sure when dev->hard_header is called.

I think dev->hard_start_xmit can include the part of dev->hard_header.
Why did the developer seperate the header building and sending frame
fucntion ?

thanks in advance.

Re: dev->hard_header ?

[Ben Greear]

Seong Moon wrote:
> In Layer 3 Protocols(eg. IP, IPv6, ...),
> they calls dev_queue_xmit() to send their data.
> 
> Before calling dev_queue_xmit(),
> does the layer 3 protocols always call dev->hard_header ?
> 
> Actually, I'm not sure when dev->hard_header is called.
> 
> I think dev->hard_start_xmit can include the part of dev->hard_header.
> Why did the developer seperate the header building and sending frame
> fucntion ?

It's not always called, this way user-space (or other parts of the kernel)
can build the headers if desired.  This at least works for ethernet and
VLAN interfaces.

Ben

> 
> thanks in advance.
> 


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Ben Greear <greearb@candelatech.com>       <Ben_Greear AT excite.com>
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