how gem5 target is built in the bootcamp 2024 tutorial

hi 
this tutorial claimed"
Prebuilt gem5 binaries:
/usr/local/bin/gem5 (gem5 ALL ISAs with CHI protocol)
/usr/local/bin/gem5-default (default gem5 ALL build with MESI_Two_Level)
/usr/local/bin/gem5-vega (x86-only with GPU protocol)
/usr/local/bin/gem5-vega-se (same as above, but compiled with 20.04)
"
but how are these target built? can someone shed a light on this?
