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Xilinx UCF area constraints disappearing

I have a design with an Aurora RocketIO core and in the UCF file I've added the following lines:

INST Inst_rio0_top/Inst_rio0/lane_0_phase_align_i/phase_align_flops_r* AREA_GROUP="PHASE_ALIGN_0_GRP";

# Place RIO0 lane_0_mgt_i at location X0Y1 INST Inst_rio0_top/Inst_rio0/lane_0_mgt_i LOC=GT_X0Y1;

AREA_GROUP "PHASE_ALIGN_0_GRP" RANGE=SLICE_X14Y152:SLICE_X15Y153;

When I use PACE to modify a pin assignment or something equally trivial and save the UCF, the AREA_GROUP "PHASE_ ..........;" line has disappeared. Although the Aurora core does still seem to work, I thought that the placement of the phase alignment FFs was important and was explicitly indicated for good reason. Can anyone tell me what's going on here please? Even if there's some setting somewhere that's telling the PAR to ignore this type of constraint, why does it disappear? Is it something to do with the fact that except for the pin assignments, all the UCF file has been added textually i.e. not via PACE or the Constraints Editor?

TIA,

Rog.

Reply to
Roger
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I am just guessing here. Are your constraints by any chance included in between the following lines?

#PACE: Start of Constraints generated by PACE ..... #PACE: End of Constraints generated by PACE

I would expect PACE to respect only whatever is outside of these lines... But I don't really know how it works in practice...

/Mikhail

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Reply to
MM

As of 6.1, the floorplanner certainly didn't respect area constraints. At least it wouldn't preserve them in any UCF it wrote back out. Maybe related, maybe not.

- Brian

Reply to
Brian Drummond

In 7.1 I was editing the assigned pins. PACE would overwrite my existing UCF file about half way through and basically made it useless. It would leave out existing constraints and hack up others by breaking them in two. I think it has a parsing issue with long lines or comments. I ended up copying my original ucf file, going in to PACE to do the pin assignments I wanted to add and then closed PACE. I'd then go and edit the ucf in the text editor and add the lines from my original ucf file that got destroyed. Something is definitely broken here?

Chuck

----- Original Message ----- From: "Roger" Newsgroups: comp.arch.fpga Sent: Friday, February 17, 2006 1:28 PM Subject: Xilinx UCF area constraints disappearing

Reply to
cwoodring

Thanks for your comments. It doesn't sound like there's an obvious answer to this one. I thought someone from Xilinx might post a comment.

Rog.

Reply to
Roger

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