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RE: [lwip-users] low level output question
From: |
John Kennedy |
Subject: |
RE: [lwip-users] low level output question |
Date: |
Fri, 8 May 2009 11:36:22 -0600 |
Ok, so what determines the length of a pbuf when it's allocated and what
determines if pbufs are chained or not, and if chained will tot_len ever exceed
the max Ethernet frame size?
Specifically, when sending an IP packet does lwip allocate a pbuf big enough
for a max Ethernet frame then set tot_len to the actual packet length?
________________________________________
John Kennedy
Idaho Technology Inc.
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USA: 1-800-735-6544
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-----Original Message-----
From: address@hidden [mailto:address@hidden
Sent: Friday, May 08, 2009 11:02 AM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] low level output question
John Kennedy wrote:
>
> In the Xilinx lwip 1.3.0 port the low_level_output function basically
> copies the entire pbuf to the Ethernetlite MAC using the pbuf len (or
> total length if the pbuf is chained). This seems inefficient, since
> the actual packet length could be much smaller than the pbuf length.
> It seems like it would be more efficient to just to copy the actual
> packet to the MAC rather than the entire pbuf. How should this be done?
>
Actual packet length == p->tot_len
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- [lwip-users] low level output question, John Kennedy, 2009/05/08
- Re: [lwip-users] low level output question, address@hidden, 2009/05/08
- RE: [lwip-users] low level output question,
John Kennedy <=
- Re: [lwip-users] low level output question, address@hidden, 2009/05/08
- RE: [lwip-users] low level output question, John Kennedy, 2009/05/08
- Re: [lwip-users] low level output question, address@hidden, 2009/05/08
- RE: [lwip-users] low level output question, John Kennedy, 2009/05/08
- Re: [lwip-users] low level output question, address@hidden, 2009/05/09
- [lwip-users] PING App Issues [RAW], HM2, 2009/05/09
- Re: [lwip-users] PING App Issues [RAW], address@hidden, 2009/05/10
- Re: [lwip-users] PING App Issues [RAW], HM2, 2009/05/10
- Re: [lwip-users] PING App Issues [RAW], Simon Goldschmidt, 2009/05/11
[lwip-users] Gratuitous ARP Target Hardware Address, HM2, 2009/05/08