Copying placement and routing between SLRs

[bn999]

I have a design targeting a vu13p which has identical functionality for each of the 4 SLRs. I have been placing and routing each SLR separately using a Vivado HD flow and piecing them all together at the end because I can get much better timing results than running the entire design at once. Sometimes one SLR run comes out with particularly good timing. I would like to reuse it on other SLRs. Device pins and glue logic (which runs at a much lower clock frequency) are overlayed during the final build stage.

Q: Could a RapidWright script be written to move everything (logic placement, BUFGs, routing) from one SLR's HD .dcp to another SLR? What would that script look like?

[eddieh-xlnx]

Hi @bn999! Great question.

In PR #245 I recently added the com.xilinx.rapidwright.design.tools.RelocationTools class which is intended to do what you're asking. It's relatively new and likely not tested in anger, so if there's something missing please report back and I'd be more than happy to help.

[bn999]

All of the methods take offset parameters (e.g. <tile_col_offset> <tile_row_offset>) relating to tile. But what type of tile are they denominated in?
What would the row_offset be if I wanted to move everything up one SLR?

[eddieh-xlnx]

One way to get this information would be to open up Vivado, and look at the height of each SLR in tiles. By clicking on a tile on the top edge and examining Tile Properties, I can see that on a xcvu13p its name is CLE_R_X115Y239 where Y239 indicates the tile row. Thus, you would want to set this offset to multiples of +/-240 so that everything is moved into the exact same position in a different SLR. Let me know how you get on!

[bn999]

So the coordinates are in CLB tile units.
First attempt, it refuses to relocate any RAM or BUFG cells and eventually failed with an error. I added one line to util/Utils.java and that seems to have fixed things:

***************
*** 387,392 ****
--- 387,393 ----
  		sliceDspBramUramTypes.addAll(dspTypes);
  		sliceDspBramUramTypes.addAll(bramTypes);
  		sliceDspBramUramTypes.addAll(uramTypes);
+ 		sliceDspBramUramTypes.addAll(moduleSiteTypes);
  	}
  
  }

I suspect that's not the proper solution, but it works.

[eddieh-xlnx]

Glad you got it working!

The lines you're referring to are:

RapidWright/src/com/xilinx/rapidwright/util/Utils.java

Lines 385 to 389 in a47e670

	sliceDspBramUramTypes = EnumSet.noneOf(SiteTypeEnum.class);
	sliceDspBramUramTypes.addAll(sliceTypes);
	sliceDspBramUramTypes.addAll(dspTypes);
	sliceDspBramUramTypes.addAll(bramTypes);
	sliceDspBramUramTypes.addAll(uramTypes);

where moduleSiteTypes is:

RapidWright/src/com/xilinx/rapidwright/util/Utils.java

Lines 324 to 344 in a47e670

	moduleSiteTypes = EnumSet.of(
	SiteTypeEnum.LAGUNA,
	SiteTypeEnum.SLICEL,
	SiteTypeEnum.SLICEM,
	SiteTypeEnum.RAMB180,
	SiteTypeEnum.RAMB181,
	SiteTypeEnum.RAMB18E1,
	SiteTypeEnum.RAMB36,
	SiteTypeEnum.RAMB36E1,
	SiteTypeEnum.RAMBFIFO18,
	SiteTypeEnum.RAMBFIFO36,
	SiteTypeEnum.RAMBFIFO36E1,
	SiteTypeEnum.FIFO18_0,
	SiteTypeEnum.FIFO18E1,
	SiteTypeEnum.FIFO36,
	SiteTypeEnum.FIFO36E1,
	SiteTypeEnum.DSP48E1,
	SiteTypeEnum.DSP48E2,
	SiteTypeEnum.BUFGCE
	// SiteTypeEnum.PS7
	);

I can see why BUFG cells are not being relocated, but it's not clear why RAM cells are not -- the difference between bramTypes and moduleSiteTypes appears to be the former is missing:

RAMB180,
RAMB181,
FIFO18_0,
FIFO36,

and the latter is missing:

RAMB18_L,
RAMB18_U

which is definitely a bug!

You've also discovered that RelocationTools is very conservative in that it only relocates DSP/BRAM/URAM and nothing else:

RapidWright/src/com/xilinx/rapidwright/design/tools/RelocationTools.java

Line 103 in a47e670

if (!Utils.sliceDspBramUramTypes.contains(si.getSiteTypeEnum())) {

Perhaps that should be enlarged to be all moduleSiteTypes (though that is far from exhaustive either!)

[eddieh-xlnx]

I've gone with a new RelocationTools.supportedTypes since it doesn't make as much sense for Laguna sites to be relocated. Proposed changes are in #294.