Having thought about it a bit more, a layout similar to the one

proposed by you may make sense.
Michael-Luke Jones  writes:
> Despite their name, Network Processing Engines are independent

quoted text
> coprocessors which are only coincidentally attached to MACs for

> ethernet / WAN purposes. If Intel would allow us to compile code for

> these coprocessors, we could get them to do lots of things other than

> networking.

Not sure about that. Intel doesn't say much about it, but I think

one can safely assume that while NPEs can probably be programmed

to do other things, their performance comes not from NPE firmware

but from specialized network coprocessors (not NPEs) which can only

do (in hardware) things like Ethernet, HDLC, bit sync, CRC16/32,

and MD5/SHA-1/DES/AES.
I think you can even use MD5 and SHA-1 without any firmware (but

would have to check this info).
Note that while certain CPUs have the same set of NPEs, they are

missing some network coprocessors and can't do, for example, crypto.
OTOH, yes, they are not, strictly speaking, only network processors.
> Crypto is not networking, and if the

quoted text
> kernel gains ixp4xx crypto support, that should be possible to enable

> independently of networking.

Yep. Unfortunately I don't know in-kernel crypto code.
> They can also function as DMA engines,

quoted text
> which should also be independent of networking functionality.

That's what the docs say. Not sure about real-life purpose of

such DMA engine, though.
> So, the NPE driver (which is basically ixp4xx specific) should be,

quoted text
> for practical purposes, networking-code agnostic. As it is a lump of

> code talking to an architecture specific piece of hardware, it should

> live in arch/arm/ rather than arch-independent drivers/

Well, I'm told that (compatible) NPEs are present on other IXP CPUs.

Not sure about details.
> As I understand it, functions to talk to the NPE should appear in the

quoted text
> NPE driver. The NPE driver should then be called by ethernet/wan/

> crypto/dma(?) drivers to carry out the specific firmware-dependent

> tasks.

Actually, the NPE code does two things:

a) initialized NPEs and downloades the firmware

b) exchanges control messages with NPEs.

--

Krzysztof Halasa

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