[libre-riscv-dev] Questions The Libre-RISCV SoC

Luke Kenneth Casson Leighton lkcl at lkcl.net
Thu Mar 21 17:55:08 GMT 2019

crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

On Thu, Mar 21, 2019 at 4:15 PM Jacob Lifshay <programmerjake at gmail.com> wrote:
> On Thu, Mar 21, 2019, 04:26 lkcl <luke.leighton at gmail.com> wrote:
> > off the top of my
> > head i can think of the following tasks:
> >
> > * an IEEE754 floating point pipeline
> >
> I think we should split this into the div/mod/sqrt/inv-sqrt pipeline
> (referred to as div pipeline hereafter) and the main pipeline. In
> particular,  I'm planning on having the div pipeline also handle integer
> div/mod and having the main pipeline handle integer multiplication and
> probably additional operations.

 recorded here http://bugs.libre-riscv.org/show_bug.cgi?id=48

> > * a basic processor core (we need a management / low-power-mode / boot-up
> > core)
> > * a nmigen pinmux (for peripheral multiplexing)
> > * a Virtual Memory Management system suitable for hybrid CPU / GPU usage
> > * a software simulator compliant with the latest SimpleV Vectorisation
> > Standard proposal
> > * design and software simulation of some of the 3D custom instructions
> > needed for the GPU
> > * Kazan 3D's software SPIR-V to LLVM compiler being operational and
> > running OpenCL applications (although this is also a massive task so
> > may need further subdivision)
> >
> I wasn't planning an OpenCL implementation until much later, if at all,
> assuming you meant Vulkan.


> Subgoals of Vulkan driver (not in any particular order):

 ok so a heck of a lot, plenty to go on, to create suitable milestones.
 recorded here http://bugs.libre-riscv.org/show_bug.cgi?id=54

> we may want to consider donating to yosys (used by nmigen and ecp5
> toolchain) and symbiflow (used as ecp5 toolchain).

 if clifford wolf had not been so absolutely astoundingly violently
and publicly rude on isa-dev, to the point where i seriously
considered reporting him for violation of google groups terms and
conditions (people actually contacted me privately to apologise for
the level of violence in his public outburst) i would agree

 additionally i contacted the director of symbiflow about the matter
and the response received was unfortunately not satisfactory.
accordingly, their behaviour may be viewed as highly unethical, and,
as such, it would be unethical to financially encourage their

> I agree on the points which I have not specifically responded to.

 ok cool.


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