Lattice "Open IP" license is GPL-compatible?

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I'm working on a new project using some code from opencores for my
thesis research. I'd love to use a nice, high-quality tiny-fsm like
picoblaze or the lattice semi micro8. However,  I'm worried about
licensing issues, as I'd also like to be able to use the opencores IP
and release the whole thing under the GPL. Does anyone know / have a
strong opinion on whether or not the Lattice Open IP license allows
the code to be incorporated into GPL'd designs? I pretty sure the
PicoBlaze does not allow this, and pacoblaze isn't so useful for those
of us in vhdl-land.

Thanks again,
   ..Eric


Re: Lattice "Open IP" license is GPL-compatible?
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IIRC, the picoblaze license says the core is free to use on Xilinx devices.
Since Xilinx's picoblaze is built straight from instantiated primitives
instead of portable HDL, Xilinx's picoblaze is completely useless on
non-Xilinx devices. I have not looked at other vendors' PSMs but I suspect
their licenses and possibly their code are both crafted along similar lines.

Since the picoblaze's license is self-enforced by design, my guess is that
you would not have any problems using the picoblaze in a GPL'd project as
long as you do not slap the GPL onto picoblaze sources or alter/remove the
existing license.

I have contemplated writing my own plain VHDL picoblaze to add a few small
features like a 16 entries stack and variable forward jump/call for a while
now but then I'd have to put together my own compiler or be stuck having to
massage the binaries between builds. (Well, I looked at pacoblaze's
homepage and it seems like it already has some of the features I am
interested in along with a java-based open-source compiler... maybe I'll
translate that to VHDL and tweak the compiler to support my own extras and
altered features.)

Re: Lattice "Open IP" license is GPL-compatible?
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  Also, the Mico8 is quite similar to PicoBlaze, so you could try
modifying that lineage ?

  Lattice have an assembler (opensource) - but last time I looked, it
was pretty annoyingly basic, but Alfred Arnold added the Mico8 to his AS
Assembler (open source), which is quite a lot better.

-jg




Re: Lattice "Open IP" license is GPL-compatible?
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It is quite trivial to write small wrappers for modules like FDCE, LUT4, and
SRL16E in portable VHDL or Verilog and then synthesize it with an ASIC flow.

Even if this wouldn't be possible you would still not be allowed to mix the
designs [1] since the Xilinx only limitation is not compatible with the GPL
requirement on no extra limitations on distribution.


/Andreas

[1] Well, it is not quite as clear cut as this. If you do this internally
    without distributing it outside of your organisation in a product or
    otherwise it should be ok. [2]
[2] IANAL applies to this one...

Re: Lattice "Open IP" license is GPL-compatible?
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This is my understanding as well, and it's a real pain if you want to
incorporate other chunks of GPL'd code (of which there are many). This
frequently results in me having to, for example, reimplement xilinx
app notes from the pdf alone and not touch the code, just so I can
then use the result.

I understand why xilinx would want to prevent someone from turning
picoblaze into an asic, or being used by competing fpga vendors. But
if the design really is optimized for xilinx primitives, then that
shouldn't be that possible without a lot of work. :) And one of the
benefits of FPGAs as a platform is you can potentially switch vendors
(although with as often as I directly instantiate things like DCMs and
BlockRAMs, that's easier said than done).

     ...Eric


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