Is there a way to disable both the thumbs? If not, then this seems like an obvious sol'n to me.

Is there a way to disable both the thumbs?

I have no idea. Gcc accepts armv6 armv6-m armv6j armv6k armv6kz armv6s-m armv6t2 armv6z armv6zk for -march however I think they all imply at least Thumb1, with some implying only a subset of Thumb2.

This comment seems quite relevent perhaps?

Currently arm-unknown-linux-gnu is sort of our "maxially compatible ARM" target, so if we're slicing out platforms (esp rpi) we may want to try to work around this another way unfortunately :(

So I tried to use a number of options to see if any of them would remove the define for thumb, sadly none of them except redefining the environment variable manually helped:

  -marm                       Generate code in 32 bit ARM state. (does not disable the THUMB define, though)
  -mno-thumb                  (CLANG ONLY: does not disable the thumb define either)
  -march=*                    Some thumb gets defined for all of them
  -D__ARM_ARCH_ISA_THUMB=0    (WORKS) Redefine manually to something else.

This is how I was testing it:

arm-none-eabi-gcc -dM -E -xc {PARAMS} /dev/null | grep THUMB

So I suppose simply adding this define for our own compiler-rt compilation is the way to go, leaving gcc-rs alone.

A small aside, I read a recommendation in multiple locations that if thumb2 is not available, -marm should be used, because thumb1 by itself is terrible and everything.

Using a different fix for now (-D__ARM_ARCH_ISA_THUMB=0 ).

@TimNN
Stop running with scissors man! The only practical user of this target is the Rpi(A,B,zero). Learn the basics before proposing any more "fixes" like this.

https://archive.is/ACutm#selection-22847.0-22865.15
https://archive.is/o2yuQ