thanks for the info, I looked at the YAML files of other platforms and eventually came across the "-netif:eth" switch. Once I had that integrated, I had a bit of a fight against the QEMU system configuration in conjunction with the UART pipe and SLIP drivers used by the networking tests, I eventually came up with a configuration in which both the UART console and the UART pipe driver work after fixing a minor bug in one of the instantiation macros of the Xilinx UART driver. Also, having the Ethernet controller driver perform polling reads/writes to a PHY that is non-existent in QEMU doesn't help the system booting. Fortunately, I had the PHY initialization as an optional switch in the driver's Kconfig file right from the start.
I don't have the exact number of tests performed available right now, but after all those changes, running sanitycheck for the tests/net branch resulted in a significant number of test cases being executed, of which only 2 or 3 failed - the actual tests all passed, but the test cases failed due to assertions. Obviously, more interfaces than expected are being created, in particular for test cases involving VLANs. I'll leave that branch as it is for now, as I'm currently doing my research regarding the two test cases in tests/kernel that currently fail.