Which .specs file is suitable for development of baremetal systems with JTAG interface ?

[johnny-wang16]

I'm trying to set up a DUT that's suitable for development of baremetal systems. The path I'm trying is the JTAG interface according to this part of chipyard documentation. However, the .specs files under chipyard/esp-tools-install/riscv64-unknown-elf/lib/ does not seem to be suitable for this use case (ex: htif_nano/nano.specs assumes an OS exist which isn't true for baremetal systems. Some specs file includes libc and some redundant libraries for dumping functionality which makes the code size unnecessarily larger. ) So, I'm wondering if there's a minimal specs file that's compatible with JTAG but without including redundant libraries. Or, if there are some documentations on how to modify the specs files. Thanks.