ChibiOS Free Embedded RTOS

This is on ChibiOS/RT trunk.

I modified syscalls.c/_write_t() with the intention to print "\r\n" if the last character is '\n', as follows:

if (ptr[len - 1] == '\n') {
sdWrite(&STDOUT_SD, (uint8_t *)ptr, (size_t)len - 1);
sdWrite(&STDOUT_SD, "\r\n", 2);
} else
{
sdWrite(&STDOUT_SD, (uint8_t *)ptr, (size_t)len);
}

I have added a printf("conn = %p\n"); to the http_server(); and this is what happens:

Program received signal SIGINT, Interrupt.
port_halt () at ../../os/ports/GCC/ARMCMx/chcore.c:43
43 }
(gdb) bt
#0 port_halt () at ../../os/ports/GCC/ARMCMx/chcore.c:43
#1 0x08000696 in chDbgPanic (msg=0x0) at ../../os/kernel/src/chdebug.c:91
#2 0x08000a06 in chSchGoSleepS (newstate=13 '\r')
at ../../os/kernel/src/chschd.c:117
#3 0x08000ae4 in chSchGoSleepTimeoutS (newstate=13 '\r', time=4294967295)
at ../../os/kernel/src/chschd.c:186
#4 0x08002ec0 in qwait (qp=0x200071f4, time=4294967295)
at ../../os/kernel/src/chqueues.c:71
#5 0x0800336c in chOQWriteTimeout (oqp=0x200071f4, bp=0x8033331 "\n", n=1,
time=4294967295) at ../../os/kernel/src/chqueues.c:400
#6 0x0800d40a in _write_r (r=0x20000108, file=1,
ptr=0x20008fa0 "conn = 0x2000a0b8\nking\n\354l\324\301\177\356\065\215$Ik\361\026\330b\375껇\031\252sGZm\375\205\061\256\\\272\024&\216*\353\016^?{t\337X\340?\302\357\366\206\254j\202\265!_\363\301\034", len=18)
at ../../os/various/syscalls.c:119
#7 0x08030f94 in __swrite ()
#8 0x0802f3b6 in _fflush_r ()
#9 0x0802fb7a in __sfvwrite_r ()
#10 0x20008e1c in ?? ()
#11 0x20008e1c in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb)

What did I overlook?

qwait() is reasonably new, maybe it tries to put the thread on the queue twice?

Regards,

Leon.

qwait() inserts only once. Is it possible that the printf() you inserted eats too much stack space and makes the webthread crash, can you should verify this? I wouldn't be surprised if takes 1-2KBs.

Giovanni

Confirmed. I think having a panic_msg for "stack overflow" makes good sense, like the (newer?) non-GCC ports for ARM seem to have.

Regards,

Leon.

Stack overflow checking is scheduled for a revision, probably it will performed in the kernel directly instead of leaving it to the port layer, I also think to add another stack checking scheme: guard pages, possibly with HW support for MCUs with MPU (all most recent Cortex-M3 and M4).

Giovanni