I had the same problem then was trying to run project based on uC OS2. So there is no problem in freeRtos or in uCOS and it is better to do change in helper.c in function:
static void do_v7m_exception_exit(CPUARMState *env) replace line env->regs[15] = v7m_pop(env); with env->regs[15] = v7m_pop(env) & 0xfffffffe; and everything will be fine. also you can pay attention to https://bugs.launchpad.net/qemu/+bug/942659 and if you already implemented byte accessed priority registers in NVIC you will be able to run even nested interrupts. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/657006 Title: arm v7M - svc insn doesn't trigger PendSV handler Status in QEMU: New Bug description: The svc instruction doesn't work as expected. -> qemu 0.13.0 rc1 (git) Test : demo with freeRTOS (for example FreeRTOS-6.0.5/Demo/CORTEX_LM3S811_GCC) with the card lm3s811evb. If we start the scheduler, it will call that function (__attribute__ (( naked ))) : void vPortStartFirstTask( void ) { __asm volatile( " ldr r0, =0xE000ED08 \n" /* Use the NVIC offset register to locate the stack. */ " ldr r0, [r0] \n" " ldr r0, [r0] \n" " msr msp, r0 \n" /* Set the msp back to the start of the stack. */ " svc 0 \n" /* System call to start first task. */ ); } The 4 first lines in asm work fine. The scv 0 call will rise the right interrupt in qemu (line 151, in arm_gic.c, best_irq = 15). However, it will never call the PendSV Handler (xPortPendSVHandler here). This function is recorded in the nvic vector. Next, (after the svc), the processor will execute the line after in code (this is a naked function) so the next function written after vPortStartFirstTask in the code. command line : console 1 : qemu-system-arm -M lm3s6965evb -kernel gcc/RTOSDemo.axf -s -S console 2 : arm-none-eabi-gdb -ex "target remote localhost:1234" gcc/RTOSDemo.axf arm-none-eabi from http://www.codesourcery.com/sgpp/lite/arm/portal/release1294 Same error with another project with arm-elf processor : arm cortex m3 host : gentoo (2.6.35-r9) (without kqemu) To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/657006/+subscriptions