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

Jamey Hicks jamey.hicks at gmail.com
Tue Apr 19 14:51:37 BST 2016


I've connected Bluespec's RISC-V implementation to the Xilinx 1Gbit/s
ethernet.

The biggest difference between connecting a UART and connecting an ethernet
is that ethernet generally requires DMA connected to the processor memory
fabric (nasti in this case).

I highly recommend starting with an ethernet core, device driver, and
configuration information that you know is working with a different
processor architecture before trying to get it working with RISC-V.

On Mon, Apr 18, 2016 at 5:44 AM Wei Song <ws327 at cam.ac.uk> wrote:

> 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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