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DMA capable Ethernet driver... (zero-copy)?
- From: "Lars Povlsen" <lpovlsen at vitesse dot com>
- To: <ecos-devel at ecos dot sourceware dot org>
- Date: Thu, 27 Jul 2006 15:00:08 +0200
- Subject: DMA capable Ethernet driver... (zero-copy)?
Hello!
On working on a.k.a. Ethernet for eCos I was initially triggered by
seeing a stack-allocated Ethernet header (redboot/stand-alone) to
investigate other Ethernet drivers... I was sad to see only copying
send() implementations until I saw the following comment in the eCos
docs:
"Note: In future, this function may be extended so that the data need
not be copied by having the function return a "disposition" code (done,
send pending, etc). At this point, you should move the data to some
"safe" location before returning."
Is this really the state of affairs? Copy no matter that the hardware
may have all kinds of fancy scatter/gather frame DMA?
I guess I may DMA the frame directly out - spinning on completion. Ouch!
Suggestions welcome...
Sincerely,
---Lars