Install Rust for Mips cross-compile in 2025

Question

I would like to install Rust cross-compile to MIPS32 little-endian. It will impress my manager. I looked at several web pages, like cross-compile for wifi pineapple but that is from 2017. How to install Rust for MIPS cross in year 2025 ? I've got 3 books on Rust and I'm reading the first.

I have a C compiler and linker and its runtime, but will accept LLVM machine machine code.

Environment:

host = ubuntu 22.04 linux
host GCC = gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
cargo: beta-x86_64-unknown-linux-gnu (default)
The currently active rustc version is rustc 1.86.0-beta.6 (8c7969a3a 2025-03-16)
admin access on host: nope, installing in my home dir.
target cpu = mips32 "mips32_1004kc" little-endian
target env = bare-metal deep embedded, no OS, no RTOS
target download: JTAG pod
existing C compiler = Green Hills
Me: been doing embedded programs and Linux for decades (and Solaris).

The main theme that is blocking me is rustup target add mips-unknown-none says your toolchain does not support target. I am confused since rustc --print=target-list | grep mips shows that target! And having "~/.cargo/config" is outdated since 2021, right?

~/Rust$ rustc --print=target-list | grep mips
mips-mti-none-elf
mips-unknown-linux-gnu
mips-unknown-linux-musl
mips-unknown-linux-uclibc
mips64-openwrt-linux-musl
mips64-unknown-linux-gnuabi64
mips64-unknown-linux-muslabi64
mips64el-unknown-linux-gnuabi64
mips64el-unknown-linux-muslabi64
mipsel-mti-none-elf
mipsel-sony-psp
mipsel-sony-psx
mipsel-unknown-linux-gnu
mipsel-unknown-linux-musl
mipsel-unknown-linux-uclibc
mipsel-unknown-netbsd
mipsel-unknown-none           <-- see, right there!!
mipsisa32r6-unknown-linux-gnu
mipsisa32r6el-unknown-linux-gnu
mipsisa64r6-unknown-linux-gnuabi64
mipsisa64r6el-unknown-linux-gnuabi64
~/Rust$ 
~/Rust$ rustup target add mipsel-unknown-none     
error: toolchain 'beta-x86_64-unknown-linux-gnu' does not support target 'mipsel-unknown-none'; did you mean 'bpfel-unknown-none'?
note: you can see a list of supported targets with `rustc --print=target-list`
note: if you are adding support for a new target to rustc itself, see https://rustc-dev-guide.rust-lang.org/building/new-target.html
~/Rust$

Places I visited and what happened:

https://spengy.net/2021/01/03/rust-on-mips.html

I already have a toolchain. Command rustup target add mips-unknown-linux-musl says toolchain does not support target.

https://docs.rust-embedded.org/embedonomicon/main.html

Wants me to run cargo new --edition 2018 --bin app . Let's move to current decade.

https://stackoverflow.com/questions/53210121/how-to-install-a-rust-target-for-a-specific-rustup-toolchain?rq=3

I tried rustup toolchain install beta-mipsel-unknown-none and got re-direction to rustup target add mipsel-unknown-none. Second command gives same "toolchain does not support target" error.