The build script seems not to install the target

During the compilation process, the following error occurred: error[E0463]: cannot find crate for core
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= note: the x86_64-rust_os target may not be installed
= help: consider downloading the target with rustup target add x86_64-rust_os

For more information about this error, try rustc --explain E0463.
error: could not compile bit_field (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile scopeguard (lib) due to 1 previous error
error: could not compile rand_core (lib) due to 1 previous error
error: could not compile bitflags (lib) due to 1 previous error
error: could not compile volatile (lib) due to 1 previous error
error: could not compile ppv-lite86 (lib) due to 1 previous error
error: could not compile byteorder (lib) due to 1 previous error
error: could not compile libm (lib) due to 1 previous error
make: *** [Makefile:89: kernel] Error 101
Is this a feature?
Perhaps improving the make script could help.
If this is intended, it would be very helpful to fix this
Thanks!