Add new target armv7-unknown-linux-uclibceabi (softfloat) by lancethepants · Pul...

This adds the new target armv7-unknown-linux-uclibceabi (softfloat). It is of course similar to armv7-unknown-linux-uclibceabihf (hardfloat) which was just recently added to rust except that it is softfloat.

My interest lies in the Broadcom BCM4707/4708/BCM4709 family, notably found in some Netgear and Asus consumer routers. The armv7 Cortex-A9 cpus found in these devices do not have an fpu or NEON support.

With this patch I've been able to bootstrap rustc, std and host tools (extended = true) to run on the target device for native compilation, allowing the target to be used as a development platform.

With the recent addition of armv7-unknown-linux-uclibceabihf (hardfloat) it looks like many of the edge cases of using the uclibc c-library are getting worked out nicely. I've been able to compile some complex projects. Some patching still needed in some crates, but getting there for sure. I think armv7-unknown-linux-uclibceabi is ready to be a tier 3 target.

I use a cross-toolchain from my project to bootstrap rust.
https://github.com/lancethepants/tomatoware
The goal of this project is to create a native development environment with support for various languages.