[Discuss OpenCPI] [UK OFFICIAL] Multiple Constraints files for a HdlConfig

From: Davis Hoover <dhoover_at_geontech.com>
Date: Mon, 27 Jan 20 10:34:58 -0500

We have only ever supported one constraints file per platform config. For
future framework improvements, your edits do provide improvement that we
might like to take advantage of.

---------- Forwarded message ---------
From: Walters Dominic A via discuss <discuss_at_lists.opencpi.org>
Date: Mon, Jan 27, 2020 at 9:46 AM
Subject: [Discuss OpenCPI] [UK OFFICIAL] Multiple Constraints files for a
HdlConfig
To: discuss_at_lists.opencpi.org <discuss_at_lists.opencpi.org>


Classification: UK OFFICIAL


Hello again,

Is it possible for a HdlConfig file to specify multiple constraints files
to be used?
I have a platform atm that has grown to 4 possible configurations, each
requiring a complete Constraints file.
These configs are largely very similar (GPIO and RAM pins and iostandards
are identical, clocks are set up the same way) with a section of FMC
related iostandard constraints and associated input delays that differ.

Currently my HdlConfig looks like this:

    <hdlconfig constraints="<file-name>">
......
    </hdlconfig>

I tried a comma separated list of constraint files, but that doesn't seem
to be supported and I struggled to find the section of ocpigen that parses
this.
The way I've gotten around this at the moment is by editing vivado-impl.tcl:

_at_ -52,7 +54,7 @@link_design -mode $mode -part $part
    puts "Loading XDC: $constraints"
- read_xdc $constraints
+ read_xdc -unmanaged $constraints
}

This allows the constraints file to be read as pure .tcl, so the .xdc file
itself is then allowed use the whole syntax of .tcl, such as:

Ø read_xdc <second_constraints_file>.xdc

Without this change vivado complains, saying that "read_xdc can't be used
in a .xdc file".
Is adding "-unmanaged" here okay?
You turn off managed design flows in vivado-synth.tcl, although I'm not
sure if that is related to this -unmanaged flag.

Thanks,
Dominic Walters

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Received on Mon Jan 27 2020 - 15:34:58 CST