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RYang28
Novice
861 Views

Compilation warning in GZip example in Intel FPGA SDK for OpenCL

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!

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7 Replies
195 Views

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
Novice
195 Views

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.
195 Views

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
Novice
195 Views

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.
195 Views

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
Novice
195 Views

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.
195 Views

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

 

Thanks,

Arslan

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