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AR# 30112

10.1 MAP - Net SAVE property behavior has changed and might lead to DRC failures

Description

Keywords: S, Save, SaveSig, Noclip, trimmed, trimming

A change has been made In ISE 10.1 to how the SAVE constraint "S" for nets is handled. Previously, the constraint blocked only the trimming of unused nets that the constraint was applied to. Beginning with ISE 10.1, the net driver and load blocks will be preserved as well. The constraint also now blocks constant optimization. It is possible that this new behavior will block some trimming or optimization that was necessary for the design to pass DRC checks. The following errors have been associated with this new behavior. In particular, some cores including ChipScope have been known to use "S" properties. ChipScope cores should either be regenerated in 10.1, or the environment variable mentioned below should be used to return to the old "s" property behavior.


ERROR:LIT:266 - SHIFTIN1 pin of ISERDES symbol "<inst>" can only be driven by an ISERDES or OSERDES

ERROR:LIT:267 - SHIFTIN2 pin of ISERDES symbol "<inst>" can only be driven by an ISERDES or OSERDES

ERROR:LIT:295 - REFCLK1 pin of GT11 symbol <inst> can only be driven by SYNCLK1OUT pin of a GT11CLK or should be left unconnected.

ERROR:LIT:296 - REFCLK2 pin of GT11 symbol <inst> can only be driven by SYNCLK2OUT pin of a GT11CLK or should be left unconnected.

ERROR:LIT:301 - EMACDCRACK pin of PPC405_ADV symbol <inst> can be driven only by pin EMACDCRACK of an EMAC.

ERROR:LIT:304 - EMACDCRDBUS bus of PPC405_ADV symbol <inst> can be driven only by bus EMACDCRDBUS of an EMAC.

ERROR:LIT:407 - CI of CARRY4 symbol "<inst>" must be driven by another CARRY4 component.

ERROR:LIT:409 - CYINIT and CI of CARRY4 symbol "<inst>" cannot be used at the same time.

ERROR:LIT:456 - The REL pin of PLL_ADV symbol "<inst>" (output signal=<sig>) must be connected to GND or left unconnected when PLL_PMCD_MODE is set to FALSE.

ERROR:LIT:458 - CRCDATAWIDTH[2] must be left unconnected or connected to GND for CRC32 symbol "<inst>" (output signal=<sig>).

ERROR:Pack:1195 - Symbol "<inst>" has no output pin connections.

ERROR:Pack:679 - Unable to obey design constraints (blah) which require the combination of the following symbols into a single SLICEM component:

Note: This Answer Record is a good match for your issue only if one of the following INFO messages is also in your MAP Report (.mrp).

INFO:MapLib:977 - SAVE has been detected on signal <sig>

INFO:MapLib:984 - SAVE has been detected on the following signal(s):

INFO:MapLib:985 - SAVE has been detected on the following signals

INFO:MapLib:986 - The SAVE constraint for nets has been made more strict starting in 10.1, such that the net driver and load blocks will be preserved as well. To revert to the original behavior please set XIL_MAP_OLD_SAVE.

Solution

When encountering this problem, first consider whether the "S" property is really necessary. If not, the solution is simply to remove the property. If the property is necessary, an environment variable is available to return to the old ISE 9.2i behavior.

Windows
SET XIL_MAP_OLD_SAVE=1

Linux and Solaris
setenv XIL_MAP_OLD_SAVE 1

For general information about setting ISE environment variables, see (Xilinx Answer 11630).
AR# 30112
Date Created 02/24/2008
Last Updated 08/27/2008
Status Active
Type General Article