[lowrisc-dev] Re: Ethernet Support on the rocket FPGA implementation

Wei Song ws327 at cam.ac.uk
Mon Apr 18 10:43:51 BST 2016


Hello Pawan,

I do not think I can provide you more information than what Stefan has
already shared.

In a tethered system, the ethernet is connected to the companion ARM core.
In a untethered system, the ethernet needs to be connected to the
Rocket-chip directly using its nasti interconnect.
There might be a need for DMA though.

Both of them need some serious work in software perhaps to bring up the
drivers.
Frankly speaking, I have not tried to connect an ethernet myself, which
Stefan actually did.

-Wei

On 17/04/2016 21:34, Pawan Reddy Sibbala wrote:
> Hello Wei,
>
> It would be great if you could give your thoughts on this. Looking
> forward to hearing from you.
>
> Thanks,
> Pawan
>
> On Tue, Apr 12, 2016 at 10:54 PM, Pawan Reddy Sibbala
> <ps849 at cornell.edu <mailto:ps849 at cornell.edu>> wrote:
>
>     Hi Wei,
>
>     I have a question about ethernet support on the rocket FPGA
>     implementation ( tethered and untethered versions ).
>
>     In the tethered version, it is mentioned that HTIF is used to
>     service system calls for peripheral device emulation. Can rocket
>     core on the FPGA send packets over the ethernet? I don't think it
>     has support for it but I'm trying to get a sense of what needs to
>     changed/added to make this support?  Could you give your thoughts
>     on how one can do this?
>
>     It seems like the untethered version has support for UART and SD
>     card. How different would it be to add ethernet support for this
>     when compared to the tethered version with HTIF?
>
>
>     Thanks,
>     Pawan
>
>
>
>
> -- 
> Pawan Reddy Sibbala
> M.Eng ECE
> Cornell University



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