To work around this issue, make the following changes in the UCF file:
1. Comment out the following constraint:
# NET "<snk_core_instant_name>/U0/pl4_lite_snk_reset0/rdclk0_rst_gen/reset_out_i*" MAXDELAY = 2.38 ns;
2. Add the following constraints in the UCF file:
INST "<snk_core_instant_name>/U0/pl4_lite_snk_reset0/rdclk0_rst_gen/reset_out*" TNM = snk_rdclk_reset;
INST "<snk_core_instant_name>/U0/pl4_lite_snk_io0/virtex*/*IDDR" TNM = snk_iddr;
TIMESPEC "TS_Snk_reset_iddr" = FROM "snk_rdclk_reset" TO "snk_iddr" "TS_RDClk_P"/ 4 DATAPATHONLY;
TIMESPEC "TS_Snk_reset_ffs" = FROM "snk_rdclk_reset" TO "FFS" "TS_RDClk_P";
Essentially, the commented MAXELAY contraint is replaced with two constraints: the non-critical reset timing path (TS_Snk_reset_iddr) and the critical reset timing path (TS_Snk_reset_ffs).
This issue has been fixed in v5.2 of the Core, available in ISE 12.1
Revision History
06/24/2009 - Initial Release