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FPorr
Beginner
690 Views

OpenCL software emulation crashes when the Kernel uses more than 6MByte of memory

Hello,

 

the OpenCL software emulation crashes with a segmentation fault when the kernel utilizes more than 6MByte of memory. Example:

uchar arr[128*128*384]; // 6MByte -- Works uchar arr[128*128*385]; // more than 6MByte -- Segmentation Fault

If this behavior is intended, a warning message would be appreciated, to prevent people from searching for a non-existing bug in their code.

 

Setup:

Ubuntu 16.04.2

Intel FPGA SDK for OpenCL 18.0.0-219

 

Tested Boards:

Arria 10 (ref BSP and BSP of custom hardware)

Stratix 10 (only BSP of custom hardware)

0 Kudos
7 Replies
159 Views

Hi,

 

May I request the testcase for replication? What is the cmd you are executing?

 

Thanks.

 

FPorr
Beginner
159 Views

Hi,

 

thank you for the reply, I attached a simple test case to reproduce the error.

The build commands I used were:

# Host application make # Kernel aoc -march=emulator krnl.cl -o bin/krnl_emu.aocx

and for execution:

CL_CONTEXT_EMULATOR_DEVICE_INTELFPGA=1 bin/host bin/krnl_emu.aocx

Depending on which size define is enabled in krnl.cl, the application either crashes or executes.

159 Views

Hi, Thanks for the attachment. Please allow me some time to look into this. Thanks. (1507183204)
159 Views

Hi, A lot has changed in the emulator since 18.0, not only in the old emulator flow (now called legacy emulator), but there is now a new emulator that replaces it in 19.1 (the fast emulator). Can you try this in 19.1 with the new fast emulator? Thanks,
159 Views

Hi, May I know if you have any updates? Thanks
FPorr
Beginner
159 Views

Hi,

 

I am sorry for the late response. I installed 19.1 but trying to compile any kernel using the fast emulator fails with:

Error: OpenCL kernel compilation FAILED

The ioc.log contains the following lines:

Using build options: -cl-std=CL1.2 -Xclang -Wuninitialized -I "/home/user/vector_add/device"

Failed to get platform id...: 0 (CL_SUCCESS)

Compilation failed!

 

Any thoughts on what might be the problem?

FPorr
Beginner
159 Views

Hi,

 

I managed to solve the problem. It did not work because I forgot to install a device ... 😟

Anyway, using the fast emulator indeed removed the problem, the application no longer crashes for data > 6MB.

Thank you for your assistance.

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