cl_peek and cl_poke usage

[marie-anne-xu]

Hi,

Are there any examples of cl_peek and cl_poke usage in a C test simulation that communicates to the SV test functions?

It seems like the previous fpga_pci_poke/peek functions (example in a custom CL) provided the functionality of the new cl_peek/poke functions. However, when the fpga_pci functions are replaced with cl_peek/poke, there is a linker error. Any examples of usage and which header files to include would be greatly appreciated, thank you!

[TrahStevAmz]

Hello marie-anne-xu,

The C test functions that you are referencing are not used in any examples in the F2 branch. What are you hoping accomplish by compiling a program that uses these functions?

A search through the F2 branch does show that the functions are declared in the cl_utils.h and cl_utils.c files.

Including the header in your source files that call cl_peek/cl_poke will at least get them declared. Compiling the cl_utils.c file in your build will get the cl_peek/cl_poke functions defined.

This F1 Makefile demonstrates this compiling in the f1_xdma_shell branch.
https://github.com/aws/aws-fpga/blob/f1_xdma_shell/hdk/cl/examples/cl_hello_world_vhdl/software/verif_rtl/Makefile

What linker error are you getting currently?
Do you get a different error if you include the cl_utils.h header in a Makefile/source file and the cl_utils.c source file in your build?
What example are you modifying to use the cl_peek/cl_poke functions?

Thanks,
Steven

[marie-anne-xu]

Hi Steven,

Thanks for the Makefile example, adding the relevant C files fixed the linking. For more context, we are using the functions to make a C program that acts like a driver to an xsim simulation. Currently, I am only running simulations on a c5.4xlarge instance, but we will eventually use the normal fpga_pci_peek/poke for an f2 instance. The program is linked in the original post, except with fpga_pci replaced with cl_peek/poke.

It looks like the cl_utils.c source file itself must be included in the makefile for our case. Using the header file will output a linker error about stdint.h not being included, as it is not included cl_utils.h but is in cl_utils.c.

For the C program and SV test to share memory, should we follow the "Accessing Host Memory during Simulation", and can we still use OCL peeks/pokes? Is there any documentation on the memory map for a C test simulation, rather than the FPGA BAR, or is it the same? For example, if we want to write to some address 0x80 over the OCL, should we add 0x80 to BAR0, and how would we get the address for BAR0 without the helper functions?

Best,
Marie-Anne

[TrahStevAmz]

Hello Marie-Anne,

I am looking into your question about the best way to use a C application to interact with an xsim simulation. There are some CL examples that include cosim C implementations that are meant to interact with a simulation (you can find these in the cl_mem_perf and cl_dram_hbm_dma examples). While these examples exist, we have not yet verified which cosim examples will work for your specific use-cases on F2, so there may be errors or extra setup steps required for you to be successful using these.

I will test these implementations and provide more detailed guidance on the best approach forward. In the meantime, feel free to explore these examples, but please note they may need modifications for your specific needs.

Thanks,
Steven