Calling ARM assembly from C, GCC (bare metal)

Question

I am trying to do some bare-metal programming in ARM with GCC and testing on QEMU. Whenever I call into an ARM label from C, my program hangs. I have a simple example of code

Answer 1

In order to call an ARM mode function defined in assembly from a THUMB mode function defined in C, you need to define a symbol in assembly as a function, and the tools (Linaro gcc) will produce a blx instruction instead of bl.

Example:

@ Here, we suppose that this part of code is inside of .code 32

.type fn, %function

fn:
   mov  pc, lr