DCMAC block enablement not respected in `service_layer.tcl`

[taraxacum45e9a]

When vbin is built with a network config that enables only eth_0, both qsfp_0_n_1 and qsfp_2_n_3 blocks are instantiated, even though only qsfp_0_n_1 should be created. This results in a Vivado build error.

[network]
eth_0=1
eth_1=0

Expected Behavior:
Only qsfp_0_n_1 is instantiated. qsfp_2_n_3 should not be created, since only eth_0 is enabled.

Actual Behavior:
Both qsfp_0_n_1 and qsfp_2_n_3 blocks are created. Build fails with:

ERROR: [BD 41-758] The following clock pins are not connected to a valid clock source:
/qsfp_2_n_3/ap_clk

Root Cause:
In service_layer.tcl:

SLASH/linker/slashkit/resources/templates/service_layer.tcl

Lines 1117 to 1168 in 4c79427

	proc add_dcmac_inst {} {
	set DCMAC0_ENABLED 1
	set DCMAC1_ENABLED 1
	## Each DCMAC can support 2 QSFP56 interfaces
	## select how many QSFP56 you want for each DCMAC, provided they are enabled
	## Setup number of QSFP56 interfaces for DCMAC0
	set DUAL_QSFP_DCMAC0 0
	## Setup number of QSFP56 interfaces for DCMAC1
	set DUAL_QSFP_DCMAC1 0
	# Create network hierarchy
	if { ${DCMAC0_ENABLED} == "1" } {
	create_qsfp_hierarchy 0 ${DUAL_QSFP_DCMAC0}
	}
	if { ${DCMAC1_ENABLED} == "1" } {
	create_qsfp_hierarchy 1 ${DUAL_QSFP_DCMAC1}
	}
	}
	# ===== Service Layer (generated) =====
	# create_service_layer ""
	# Absolute paths (normalized)
	set ::slash_dcmac_tcl [file normalize "{{ dcmac_tcl }}"]
	set ::slash_dcmac_hdl [file normalize "{{ dcmac_hdl_dir }}"]
	# Source the DCMAC Tcl helpers
	source $::slash_dcmac_tcl
	{% for vf in dcmac_hdl_files %}
	import_files -fileset sources_1 -norecurse [file normalize "{{ vf }}"]
	{% endfor %}
	# --- Drive DCMAC creation based on config ---
	{% if needs_dcmac %}
	set DCMAC0_ENABLED {{ dc_enable_0 }}
	set DCMAC1_ENABLED {{ dc_enable_1 }}
	set DUAL_QSFP_DCMAC0 {{ dual_qsfp_0 }}
	set DUAL_QSFP_DCMAC1 {{ dual_qsfp_1 }}
	# Calls proc add_dcmac_inst which expects the above variables
	add_dcmac_inst
	{% else %}
	set DCMAC0_ENABLED 0
	set DCMAC1_ENABLED 0
	set DUAL_QSFP_DCMAC0 0
	set DUAL_QSFP_DCMAC1 0
	# Ethernet disabled; no DCMAC hierarchy created.
	{% endif %}

• DCMAC0_ENABLED and DCMAC1_ENABLED are correctly set based on config at lines 1155–1156.
• However, these values are not propagated when used at line 1161.
• Instead, they are unconditionally overridden at lines 1119–1120. As a result, whenever any network interface is enabled, both QSFP blocks are instantiated.

Impact:
Any build enabling only a single DCMAC/ethernet interface will fail.

[mariodruiz]

Hi @taraxacum45e9a, we are looking at making changes to the DCMAC logic. For now, we suggest not to make changes to this part.