Error: Target CPU does not support ARM mode

c gcc arm cortex-m3 codesourcery
Brandon Yates picture Brandon Yates · Mar 6, 2012 · Viewed 26.4k times · Source

I'm trying to cross=compile a simple program with inline assembly for a variety of ARM processors. It contains the assembly instruction QSUB which according to this document is both a valid ARM and Thumb-2 instruction.

This compiles fine for me when building for a cortex-a8.

I get the compile error in the title when I try building for a cortex-m3 and can't figure out why. I attempted to force thumb mode with the compiler switch -mthumb, and then the error changes to "selected processor does not support thumb mode." I'm a bit confused because cortex-m3 does in fact support thumb mode.

Here's the compile options I'm using with codesourcery's gcc:

arm-none-linux-gnueabi-gcc helloworld.c -o a.out -lm -mthumb -mcpu=cortex-m3

Answer

Michael Burr picture Michael Burr · Mar 6, 2012

QSUB is not mentioned in ARM's "Cortex-M3 Devices Generic User Guide" (Document DUI0552A).

Additionally, TI's "Cortex-M3/M4F Instruction Set, TECHNICAL USER'S MANUAL" indicates that QSUB is not supported on the Cortex-M3.

I think you're just going to have to believe what GCC is telling you...

Related questions

How to place a variable at a given absolute address in memory (with GCC)

The RealView ARM C Compiler supports placing a variable at a given memory address using the variable attribute at(address): int var __attribute__((at(0x40001000))); var = 4; // changes the memory located at 0x40001000 Does GCC have a similar variable attribute?

Read More
How to work with external libraries when cross compiling?

I am writing some code for raspberry pi ARM target on x86 ubuntu machine. I am using the gcc-linaro-armhf toolchain. I am able to cross compile and run some independent programs on pi. Now, I want to link my code …

Read More
memory alignment within gcc structs

I am porting an application to an ARM platform in C, the application also runs on an x86 processor, and must be backward compatible. I am now having some issues with variable alignment. I have read the gcc manual for __…

Read More