Compilation warning in GZip example in Intel FPGA SDK for OpenCL

RYang28 · ‎03-01-2019

Hi,

Recently, I'm trying the Intel FPGA SDK for OpenCL on Arria 10 boards. When I compile the GZip example with default flags stated in the readme.html. I got the warning msg below:

Compiling for FPGA. This process may take a long time, please be patient.
Warning: hold time violation of -0.038 ns on clock:
  board_inst|kernel_clk_gen|kernel_clk_gen|kernel_pll|outclk0
See /opt/intelFPGA_pro/18.1/hld/examples_aoc/gzip/bin/gzip/top.failing_clocks.rpt for more details.
This could potentially cause funcitonal failures.  Consider recompiling with a
different seed (using -seed=<S>).
aoc: Hardware generation completed successfully.

At last, the example can be executed successfully. However, I'm still worried about this warning because it is a big problem if the compression file might not be decompressed in our application. So can anyone give me some advice on this?

BTW, I've managed to find a seed (by randomly guessing) that won't generate this warning. But can I consider the possibility of funcitonal failures is zero then?

Thanks a lot!

MuhammadAr_U_Intel · ‎04-24-2019

Is there any other timing violation in the report ? Did you tried re-compiling the design with same settings to see if the timing violations are there ? Also what version of OpenCL SDK are you using ?

RYang28 · ‎04-25-2019

Hi MUsman, 1. No other timing violations 2. Tried tens of times, the timing violation is always shown with no -seed option. 3. 18.1.1.263 Thanks for the help.

MuhammadAr_U_Intel · ‎04-29-2019

Hi, What command are you using to compile, I got Error for insufficient resources during the compilation targeting A10 board. aoc device/gzip.cl -o bin_a10_hw/gzip.aocx -DVEC=16 -DENGINES=4 -DLOW_BANDWIDTH_DEVICE=1 -board=a10gx Thanks, Arslan

RYang28 · ‎04-29-2019

Hi MUsman, The flags you used is for S10 (you got them from readme I think). But A10 can only be compiled with ENGINES=1, -D flags I used are -DVEC=16 -DENGINES=1, (no need for -DLOW_BANDWIDTH_DEVICE). Have a try, thanks.

MuhammadAr_U_Intel · ‎05-02-2019

Hi, I have tried compilation using Compiler version 18.1 build 222 and 19.1 build 240 I didn't see any Warning for timing violation, here is the command I used. aoc device/gzip.cl -o bin_a10_hw/gzip.aocx -DVEC=16 -DENGINES=1 -board=a10gx -v Thanks, Arslan

RYang28 · ‎05-06-2019

Hi MUsman, I've tried to compile against the a10_ref bsp in the SDK, and got the same output as yours with no hold time violations. Then I think the problem may be related to the bsp provided by the board vendor. Thanks for the help.

MuhammadAr_U_Intel · ‎05-06-2019

Yes you got it correct, you need to check with the BSP provider on this Warning.

Thanks,

Arslan