Hi,

My impression is that proprietary EDA software produces a lot of
pointless warnings all the time, and that the specification of what
causes a warning and what does not varies widely from EDA program to EDA
program.

Adding proper support for suppressing those warnings:
1) is a lot of work as one would need to understand all the
idiosyncrasies of every common EDA program
2) makes the Migen Verilog backend more complex and harder to understand
3) makes the backend less maintainable
4) is a low-importance feature

The asic_syntax patch was marginally acceptable as it is simple enough,
and I understand the need for removing features such as register
initialization that have no equivalent in ASIC and may cause synthesis
tool errors or simulation/synthesis mismatches. But I do not think we
should go much further in this direction.

I think that the development time would be much better spent getting rid
of the proprietary Verilog synthesizers, which is definitely feasible
for FPGA targets.

HardCaml already has such a feature:
http://www.ujamjar.com/hardcaml/introduction.html#Transformation
Migen has a EDIF backend (for those designs that consist exclusively of
instances):
https://github.com/m-labs/migen/blob/master/migen/fhdl/edif.py
and there was an effort to implement direct synthesis in Migen:
https://github.com/nakengelhardt/mist

Sébastien


On 04/22/2015 11:12 PM, Florent Kermarrec wrote:
> Hi,
> 
> we should have something more generic for syntax specialization. (we
> sometimes want some of the features added with asic_syntax for FPGA
> targets to avoid polluting synthesis with warnings).
> 
> Here are two patches to try to be more generic. In the second patch, the
> async_syntax test is renamed to test_syntax and can be used as our
> syntax test for all supported syntax specializations.
> 
> What do you think about that?
> 
> Regards,
> 
> Florent

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