floating point operations cause unaligned usage fault

Jurgen, your linker command line is incorrect. Please use arm-none-eabi-gcc
as linker and give -mthumb -mcpu=cortex-m3 as command line.

More details please follow readme or samples.

Thanks
Joey
On Jan 13, 2014 11:58 PM, "Jürgen Funck" <
<email address hidden>> wrote:

> New question #242149 on GCC ARM Embedded:
> https://answers.launchpad.net/gcc-arm-embedded/+question/242149
>
> Hello everybody,
>
> I'm experiencing problems when using floating point operations on a cortex
> m3 processor (STM32F105 to be precise).
>
> Debugging with the gdb tells me that a hard fault is generated inside the
> routine __mulsf3 which seems to be a part of the gcc soft floating point
> library. Here is the complete output from the gdb.
>
> (gdb) info frame
> Stack level 0, frame at 0x20004fc8:
> pc = 0x80010a8 in HardFault_Handler (stm32f10x_it.c:61); saved pc
> 0xfffffff9
> called by frame at 0x20004fe8
> source language c.
> Arglist at 0x20004fc8, args:
> Locals at 0x20004fc8, Previous frame's sp is 0x20004fc8
> (gdb) info frame 0x20004fe8
> Stack frame at 0x20004fe8:
> pc = 0x800110c in __mulsf3
> (../../../gcc-4.5.1/libgcc/../gcc/config/arm/ieee754-sf.S:452); saved pc
> 0x8000164
> called by frame at 0x20005000, caller of frame at 0x20004fe8
> source language asm.
> Arglist at 0x20004fe8, args:
> Locals at 0x20004fe8, Previous frame's sp is 0x20004fe8
>
> Examining the fautl status register of the cortex m3 tells me that the
> cause is "Unaligned access UsageFault":
> Here is the complete output for the UsageFault status register:
>
> (gdb) x /ht 0xe000ed2a
> 0xe000ed2a: 0000000100000000
>
> Does anybody have an idea why this is happening? Is this likely to be a
> bug in the gcc or a related library, or is something going wrong during
> compilation of the program?
>
> Here is the example program I'm using:
>
> int main(void)
> {
> volatile uint32_t i;
> volatile float x,y;
>
> /* GPIOC Periph clock enable */
> RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
>
> /* Configure PC12 in output pushpull mode */
> GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
> GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
> GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
> GPIO_Init(GPIOC, &GPIO_InitStructure);
>
> while (1)
> {
> /* Set PC12 */
> GPIOC->BSRR = 1 << 1;
>
> x = 2.5;
> y = 0.2;
>
> i = 1000000;
> while(--i);
>
> /* Reset PC12 */
> GPIOC->BRR = 1 << 1;
>
> y = y*x;
>
> i = 2000000;
> while(--i);
> }
> }
>
> This the output during compilation:
> $ make
> .compiling
> arm-none-eabi-gcc -Wall -fno-common -c -g -mcpu=cortex-m3 -mthumb -g -O0
> -I./ -I./lib/ -I./lib/inc/ -I./lib/inc/../../ -DTRACE_LEVEL=4 -o obj/main.o
> main.c
> arm-none-eabi-gcc -Wall -fno-common -c -g -mcpu=cortex-m3 -mthumb -g -O0
> -I./ -I./lib/ -I./lib/inc/ -I./lib/inc/../../ -DTRACE_LEVEL=4 -o
> obj/system_stm32f10x.o system_stm32f10x.c
> arm-none-eabi-gcc -Wall -fno-common -c -g -mcpu=cortex-m3 -mthumb -g -O0
> -I./ -I./lib/ -I./lib/inc/ -I./lib/inc/../../ -DTRACE_LEVEL=4 -o
> obj/stm32f10x_it.o stm32f10x_it.c
> .compiling libraries
> arm-none-eabi-gcc -Wall -fno-common -c -g -mcpu=cortex-m3 -mthumb -g -O0
> -I./ -I./lib/ -I./lib/inc/ -I./lib/inc/../../ -DTRACE_LEVEL=4 -o
> obj/stm32f10x_gpio.o ./lib/src/stm32f10x_gpio.c
> arm-none-eabi-gcc -Wall -fno-common -c -g -mcpu=cortex-m3 -mthumb -g -O0
> -I./ -I./lib/ -I./lib/inc/ -I./lib/inc/../../ -DTRACE_LEVEL=4 -o
> obj/stm32f10x_rcc.o ./lib/src/stm32f10x_rcc.c
> ..linking
> arm-none-eabi-ld -g -v -nostartfiles -Map ./main.map
> -T./lib/stm32_flash.ld -o ./main.out obj/main.o obj/system_stm32f10x.o
> obj/stm32f10x_gpio.o obj/stm32f10x_rcc.o obj/stm32f10x_it.o
> obj/startup_stm32f10x_md.o libgcc.a
> GNU ld (GNU Tools for ARM Embedded Processors) 2.23.2.20131129
> arm-none-eabi-objcopy -O binary ./main.out ./main.bin
> arm-none-eabi-objdump -x --syms -S ./main.out > ./main.list
> ...completed.
>
> Regards,
>
> Jürgen
>
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