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Ethernet stack sends empty fragment
- From: Timo Gerber <timo dot gerber at x2e dot de>
- To: ecos-discuss at ecos dot sourceware dot org
- Date: Mon, 01 Mar 2010 11:27:59 +0100
- Subject: [ECOS] Ethernet stack sends empty fragment
Hi guys,
I'm working on an ethernet driver with scather gather support and I am
wondering:
When sending UDP packets from the application with a higher payload-size
(e.g. 2500Bytesand more), the ethernet stack calls my DRV_eth_send()
function with a weird sg_list.
For instance, some packets are fragmented like this:
sg_list[1].len => 42
sg_list[1].buf => points to the hdr.
sg_list[2].len => 1472
sg_list[2].buf => points to the payload.
sg_list[3].len => 0
sg_list[3].buf => points to an empty buffer.
As you can see the last sg fragment is kinda weird, but this scheme
appears all the time, not only now an then.
Timo
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