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Registered: ‎04-24-2014

KCPSM6 on Kintex7 - mapping error



I ported one of my designs from Virtex-5 / Virtex-6 to our new Kintex-7 board. This design employes a PicoBlaze KCPSM6 with constraints.


xst -> all ok

translate -> all ok

map -> error


here is the message:

The directed pack was not possible because: The top reasons for failure were:
-> A legal placement was never found for LUT symbol "PT/SoFPGA/PicoBlaze/address_loop[0].lsb_pc.high_int_vector.pc_lut".
-> A legal placement was never found for LUT symbol "PT/SoFPGA/PicoBlaze/address_loop[1].upper_pc.high_int_vector.pc_lut".
-> A legal placement was never found for LUT symbol "PT/SoFPGA/PicoBlaze/address_loop[2].upper_pc.high_int_vector.pc_lut".
-> A legal placement was never found for LUT symbol "PT/SoFPGA/PicoBlaze/address_loop[3].upper_pc.high_int_vector.pc_lut".
-> The DI signal PT/SoFPGA/PicoBlaze/pc_mode<0> on CYMUX PT/SoFPGA/PicoBlaze/address_loop[0].lsb_pc.pc_muxcy has a conflict with the AX pin and the O5 output of the A LUT is not available for a route-through.


Has anyone noticed a similar error. If I'm not mistaken a 7-Series Slice should be a superset of a Virtex-5/6 Slice....



Best regards

     Patrick Lehmann

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2 Replies
Xilinx Employee
Xilinx Employee
Registered: ‎09-05-2007

If this was reported as a 'Pack:2811' error, then yes, this is covered as a 'Known Issue' with workarounds in the 'READ_ME_FIRST.txt' file provided in the KCPSM6 package. If it was something different then I'd need to see and know a bit more information.


KCPSM6 is suitable for use with Spartan-6, Virtex-6, 7-Series and UltraScale devices. I assume you meant that you replaced KCPSM3 with KCPSM6 when moving from Virtex-5; the details in the messages you provided certainly indicate that you are using KCPSM6 in your design now.





Ken Chapman
Principal Engineer, Xilinx UK
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Registered: ‎04-24-2014

Sorry for my late response.


I'm actually using KCPSM6 on Virtex-5 (unconstrainted version) as well. There are no problems so far.



Yes, it's a Pack:2811 error. After posting my last message I found several posts in this forum addressing this issue, sorry again.


I also read your post: PicoBlaze FAQ - 'Pack:2811' error in MAP

Regarding your workarounds:

a) ChipScope is somewhere in the design, but not directly connected to the PicoBlaze

b) This was a good point - I recreated the project from scratch and forgot to select/deselect some xst, map and par options. So now xst is again in Keep Hierarchy = Soft mode :)


I also changed two other settings:

- In my ILA IP-Core (ChipScope), I disabled RPMs (relationally placement macros), because the are often related to pack:2811 errors.

- I also had an other mapping problem caused by a GTXE2 transceiver in a Kintex-7 device.


The latter one was hard to find because it generated several mapping errors, which where not really assoziated with the GTXE2 tranceiver. The bug is in the Kintex-7 / KC705 documentation: RX_n and RX_p pins for GTXE2_CHANNEL_X0Y10 are swaped!


So I'm not sure which change fixed the pack:2811 error, but KCPSM6 is working again.



Best regards

     Patrick Lehmann

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