@zjenny09 remember that arch-defs is meant for making sure that the toolchain is capable of building a bitstream for a design with certain features, so the litex design will only build you the bitstream of the Linux capable LiteX SoC. When it comes to booting Linux on the bitstream you built and uploaded to the board please refer to linux-on-litex-vexrsicv. I suggest you use Ethernet instead of serial for uploading the kernel, devicetree, etc. as it is much faster. You can find a description of how to setup TFTP in the symbiflow-examples documentation.