--connectivity Options - 2020.2 English

--connectivity.nk

--connectivity.nk <arg>

Where <arg> is specified as <kernel_name>:#:<cu_name1>.<cu_name2>...<cu_name#>.

This instantiates the specified number of CU (#) for the specified kernel (kernel_name) in the generated FPGA binary (.xclbin) file during the linking process. The cu_name is optional. If the cu_name is not specified, the instances of the kernel are simply numbered: kernel_name_1, kernel_name_2, and so forth. By default, the Vitis compiler instantiates one compute unit for each kernel.

For example:

v++ --link --connectivity.nk vadd:3:vadd_A.vadd_B.vadd_C

[connectivity]
nk=vadd:3:vadd_A.vadd_B.vadd_C

--connectivity.slr

--connectivity.slr <arg>

Use this option to assign a CU to a specific SLR on the device. The option must be repeated for each kernel or CU being assigned to an SLR.

Valid values include:

<cu_name>:<SLR_NUM>

Where:

• <cu_name> is the name of the compute unit as specified in the --connectivity.nk option. Generally this will be <kernel_name>_1 unless a different name was specified.
• <SLR_NUM> is the SLR number to assign the CU to. For example, SLR0, SLR1.

For example, to assign CU vadd_2 to SLR2, and CU fft_1 to SLR1, use the following:

v++ --link --connectivity.slr vadd_2:SLR2 --connectivity.slr fft_1:SLR1

[connectivity]
slr=vadd_2:SLR2
slr=fft_1:SLR1

--connectivity.sp

--connectivity.sp <arg>

Use this option to specify the assignment of kernel interfaces to system ports within the platform. A primary use case for this option is to connect kernel ports to specific memory resources. A separate --connectivity.sp option is required to map each interface of a kernel to a particular memory resource. Any kernel interface not explicitly mapped to a memory resource through the --connectivity.sp option will be automatically connected to an available memory resource during the build process.

Valid values include:

<cu_name>.<kernel_interface_name>:<sptag[min:max]>

Where:

• <cu_name> is the name of the compute unit as specified in the --connectivity.nk option. Generally this will be <kernel_name>_1 unless a different name was specified.
• <kernel_interface_name> is the name of the function argument for the kernel, or compute unit port.
• <sptag> represents a system port tag, such as for memory controller interface names from the target platform. Valid <sptag> names include DDR, PLRAM, and HBM.
• [min:max] enables the use of a range of memory, such as DDR[0:2]. A single index is also supported: DDR[2].

The following example maps the input argument (A) for the specified CU of the VADD kernel to DDR[0:3], input argument (B) to HBM[0:31], and writes the output argument (C) to PLRAM[2]:

v++ --link --connectivity.sp vadd_1.A:DDR[0:3] --connectivity.sp vadd_1.B:HBM[0:31] \
--connectivity.sp vadd_1.C:PLRAM[2]

[connectivity]
sp=vadd_1.A:DDR[0:3]
sp=vadd_1.B:HBM[0:31]
sp=vadd_1.C:PLRAM[2]

--connectivity.sc

--connectivity.sc <arg>

Create a streaming connection between two compute units through their AXI4-Stream interfaces. Use a separate --connectivity.sc option for each streaming interface connection. The order of connection must be from a streaming output port of the first kernel to a streaming input port of the second kernel. Valid values include:

<cu_name>.<streaming_output_port>:<cu_name>.<streaming_input_port>[:<fifo_depth>]

Where:

• <cu_name> is the compute unit name specified in the --connectivity.nk option. Generally this will be <kernel_name>_1 unless a different name was specified.
• <streaming_output_port>/<streaming_input_port> is the function argument for the compute unit port that is declared as an AXI4-Stream.
• [:<fifo_depth>] inserts a FIFO of the specified depth between the two streaming ports to prevent stalls. The value is specified as an integer.

For example, to connect the AXI4-Stream port s_out of the compute unit mem_read_1 to AXI4-Stream port s_in of the compute unit increment_1, use the following:

--connectivity.sc mem_read_1.s_out:increment_1.s_in

[connectivity]
sc=mem_read_1.s_out:increment_1.s_in

The inclusion of the optional <fifo_depth> value lets the v++ linker add a FIFO between the two kernels to help prevent stalls. This will use BRAM resources from the device when specified, but eliminates the need to update the HLS kernel to contain FIFOs. The tool will also instantiate a Clock Converter (CDC) or Datawidth Converter (DWC) IP if the connections have different clocks, or different bus widths.