I am writing some test code to get a feel for how different HAL APIs work, and right now I am working on the RTC interface.
I am using an STM32F1xx (103RB), with arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors) 4.8.3 20140228 (release), and ChibiOS/RT 2.6.7.
Everything so far is working as expected. I can set and get the rtc time and alarm, and the fat time, from main() after chSysInit(). I can also enable the callback, which works as expected, except for one thing, I get a stack overflow if my chprintf() string is too long inside the callback:
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void rtc_alarm_handler(RTCDriver *rtcp, rtcevent_t event) {
RTCAlarm rtcalarm;
if (event == RTC_EVENT_ALARM) {
chprintf(SD2bssp,"Alarm Handler: Alarm Expired! Set again.\n");
// NOTE the above printf string causes a stack overflow...
// The one below DOESN'T overflow
// chprintf(SD2bssp,"ALARM\n");
rtcGetAlarm(rtcp,0,&rtcalarm);
rtcalarm.tv_sec += 30;
rtcSetAlarm(rtcp,0,&rtcalarm);
}
return;
}
The backtrace gives:
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(gdb) bt
#0 0x08000352 in port_halt () at ../.././ChibiOS-RT/os/ports/GCC/ARMCMx/chcore.c:48
#1 0x08000668 in chDbgPanic (msg=msg@entry=0x8002080 "stack overflow") at ../.././ChibiOS-RT/os/kernel/src/chdebug.c:274
#2 0x08000806 in chSchGoSleepS (newstate=<optimized out>) at ../.././ChibiOS-RT/os/kernel/src/chschd.c:128
#3 0x08000852 in chSchGoSleepTimeoutS (newstate=newstate@entry=13 '\r', time=<optimized out>) at ../.././ChibiOS-RT/os/kernel/src/chschd.c:202
#4 0x08000c30 in qwait (qp=<optimized out>, time=<optimized out>) at ../.././ChibiOS-RT/os/kernel/src/chqueues.c:76
#5 0x08000db4 in chOQPutTimeout (oqp=0x20000e50 <SD2+48>, b=<optimized out>, time=4294967295) at ../.././ChibiOS-RT/os/kernel/src/chqueues.c:335
#6 0x08001854 in chvprintf (chp=0x20000e20 <SD2>, fmt=0x800214b "m Expired! Set again.\n", fmt@entry=0x55555555 <Address 0x55555555 out of bounds>, ap=..., ap@entry=...)
at ../.././ChibiOS-RT/os/various/chprintf.c:129
#7 0x08001a94 in chprintf (chp=<optimized out>, fmt=0x8002138 "Alarm Handler: Alarm Expired! Set again.\n") at ../.././ChibiOS-RT/os/various/chprintf.h:73
#8 0x08001af8 in rtc_alarm_handler (rtcp=0x20000e1c <RTCD1>, event=<optimized out>) at main.c:42
#9 0x080013f4 in Vector4C () at ../.././ChibiOS-RT/os/hal/platforms/STM32/RTCv1/rtc_lld.c:116
#10 <signal handler called>
#11 0x55555554 in ?? ()
#12 0x55555554 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
I think that maybe I need to increase the stack size for whatever stack is being used by the callback. I tried adding #define PORT_INT_REQUIRED_STACK 128 to chconf.h, but this doesn't solve the problem. My question is, where should I be looking to modify the stacks appropriately, if that is the issue, and if it isn't, what should I be looking for?
Other code in main() just reads the rtc time, sys time and alarm, and prints to SD2 with chprintf. Also the typical example blinker thread is running. Let me know if more details are needed.
Thanks!
-Stephen
