Peter C. Wallace wrote: > On Wed, 31 Oct 2007, Jon Elson wrote: > > >>Date: Wed, 31 Oct 2007 12:43:44 -0600 >>From: Jon Elson <[EMAIL PROTECTED]> >>Reply-To: "Enhanced Machine Controller (EMC)" >> <emc-users@lists.sourceforge.net> >>To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> >>Subject: Re: [Emc-users] Ethernet I/O >> >>Peter C. Wallace wrote: >> >>> >>>But for point to point, all you do is setup the packet in memory, setup the >>>DMA controller and tweak the Enet chip >>> >> >>But, the Ethernet driver has to be running as a process under >>the real time system. >> >>Jon > > > All I'm saying is that for raw packets (no TCPIP no UDP no ARP no nothing) > What the driver has to do is not much more than with paralllel or other > hardware. Indeed, maybe less. The packets could be pre-built at startup time, and just the values stuffed in, the Ethernet MAC does all the work. But, such a stripped-down driver doesn't exist, as far as I know. When you get down to having to configure the PC's DMA controller and all the tiny details in the ethernet chip, it can get a bit complicated. Then, you have to support a dozen different ethernet MAC chips, too. I really am not going to do it at that level, the support headache is WAY too big. The PC parallel port is basically a fixed architecture. If it supports EPP, that's all you need to know, Microsoft wrote the register-level spec on that and they all are supposed to comply. Not so with the Ethernet MAC, for instance RTnet supports 12 different MAC chips. UGH!
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