Generating ARMv2 code with a gcc cross-compiler

ARMv2

$ cat regs.c
typedef unsigned int uint32;

#define BLTCON1 *((volatile uint32 *)0xFFFFFF00)
#define BLTCON2 *((volatile uint32 *)0xFFFFFF04)
#define BLTCON3 *((volatile uint32 *)0xFFFFFF08)

void foo(uint32 x, uint32 y, uint32 z) {
	BLTCON1 = x;
	BLTCON2 = y;
	BLTCON3 = z;
}
$ armeb-unknown-eabi-gcc -march=armv2 -O2 -S -Wall -Wextra -Wundef -Wconversion -pedantic-errors -std=c99 regs.c
regs.c:1: warning: target CPU does not support interworking
$ cat regs.s 
	.arch armv2
	.fpu softvfp
	.eabi_attribute 20, 1
	.eabi_attribute 21, 1
	.eabi_attribute 23, 3
	.eabi_attribute 24, 1
	.eabi_attribute 25, 1
	.eabi_attribute 26, 1
	.eabi_attribute 30, 2
	.eabi_attribute 18, 4
	.file	"regs.c"
	.text
	.align	2
	.global	foo
	.type	foo, %function
foo:
	@ args = 0, pretend = 0, frame = 0
	@ frame_needed = 0, uses_anonymous_args = 0
	@ link register save eliminated.
	mvn	r3, #0
	str	r0, [r3, #-255]
	str	r1, [r3, #-251]
	str	r2, [r3, #-247]
	mov	pc, lr
	.size	foo, .-foo
	.ident	"GCC: (crosstool-NG 1.19.0) 4.3.2"
$ 

HOWTO

wget http://crosstool-ng.org/download/crosstool-ng/crosstool-ng-1.19.0.tar.bz2
bunzip2 -c crosstool-ng-1.19.0.tar.bz2 | tar xf -
cd crosstool-ng-1.19.0
./configure --enable-local
make
./ct-ng armeb-unknown-eabi
./ct-ng build
export PATH=${PATH}:${HOME}/x-tools/armeb-unknown-eabi/bin
armeb-unknown-eabi-gcc -march=armv2 ...

Compiled with -march=armv2 , so this startup routine needs to be converted to a non-thumb instruction set.

||=== HelloWorld, Debug ===|
Setup\startup.S|1|warning: target CPU does not support THUMB instructions [enabled by default]|
Setup\startup.S|84|Error: selected processor does not support ARM mode `bx r0'|
Setup\startup.S|111|Error: selected processor does not support ARM mode `mrs r0,cpsr'|
Setup\startup.S|113|Error: selected processor does not support ARM mode `msr cpsr,r0'|
Setup\startup.S|118|Error: selected processor does not support ARM mode `bx r2'|
Setup\startup.S|128|Error: selected processor does not support ARM mode `bx lr'|
Setup\startup.S|145|Error: selected processor does not support ARM mode `msr CPSR_c,#ARM_MODE_UNDEF|I_BIT|F_BIT'|
Setup\startup.S|148|Error: selected processor does not support ARM mode `msr CPSR_c,#ARM_MODE_ABORT|I_BIT|F_BIT'|
Setup\startup.S|151|Error: selected processor does not support ARM mode `msr CPSR_c,#ARM_MODE_FIQ|I_BIT|F_BIT'|
Setup\startup.S|154|Error: selected processor does not support ARM mode `msr CPSR_c,#ARM_MODE_IRQ|I_BIT|F_BIT'|
Setup\startup.S|157|Error: selected processor does not support ARM mode `msr CPSR_c,#ARM_MODE_SVC|I_BIT|F_BIT'|
Setup\startup.S|167|Error: selected processor does not support ARM mode `bx r0'|
||=== Build finished: 11 errors, 1 warnings (0 minutes, 0 seconds) ===|