MSP430 missing MSP430X instruction set

I tried to build a simple "Hello, World" application that simply blinks a light as a basic entry point to doing Rust development work on the MSP430FR5994. After figuring out how to compile 'libmsp430' and installing the msp430-elf binutils and gcc, I started trying to compile my code, only to realize that Rust currently only supports the 16-bit MSP430 instruction set, and not the 20-bit MSP430X instruction set. Trying to set mcpu did not work. Eventually, I just linked it against the crt0 for the 16-bit base MSP430 instruction set and decided to use the 16-bit instruction set. Does anybody know how to resolve this? Will it require a new target?

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rustc --version --verbose:

rustc 1.98.0-nightly (6368fd52c 2026-05-29)
binary: rustc
commit-hash: 6368fd52cb9f230dfb156097625993e7a8891800
commit-date: 2026-05-29
host: aarch64-unknown-linux-gnu
release: 1.98.0-nightly
LLVM version: 22.1.6

Start by reproducing the reported build for the MSP430FR5994 and compare the existing 16-bit MSP430 support with the requested MSP430X instruction set. Investigate whether mcpu configuration or a new target is needed, using the msp430-elf binutils and gcc setup described in the report. Done means Rust can compile a simple application targeting MSP430X with correct instruction-set support.