Bill Leckey wrote:
I've been coding an ethernet driver for some new hardware we're
developing and while it's working, there are a few issues I'm still
unsure of. I couldn't find any archives for this list, so I'm
suspecting I'm going to cover a lot of 'old ground'. Most of my info
for coding ethernet drivers comes out of Rubini and Corbet's LInux
Device Drivers, and what I've gleaned from kernel sources
Firstly some background. With these cards I can have up to 25 point to
point connections (to the same destination machine, or 25 destination
machines). I have almost total control of what goes out on the wire, so
I've chosen a minimal header that contains the type (passed in to
hard_header) and a 16 bit field that contains misc other information.
So, 32 bits, plus the data. The hardware provides things like length,
and CRC checking.
Currently I'm setting dev->hard_header_len to 4.
The part that concerns me is what I set dev->type, dev->addr_len and
dev->flags to.
We don't technically have a hardware address so I set dev->addr_len to 0.
If you want to look like ethernet, it seems you would want at least a fake
MAC. To me, it also sounds like you may want up to 25 net_devices, since
you have that many logical point-to-point connections. (Similar to the
way VLAN works)
I set dev->type to ARPHRD_VOID, simply because I'm not sure what the
consequences of setting it to anything else are.
Maybe you could get a serial number out of your device and then hash it
into MAC addresses? The user can always change these with ifconfig or 'ip'
after your device initializes anyway...
--
Ben Greear <greearb@xxxxxxxxxxxxxxx> <Ben_Greear AT excite.com>
President of Candela Technologies Inc http://www.candelatech.com
ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear
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