eCos applications and components can be debugged in traditional ways, with printing statements and debugger single-stepping, but there are situations in which these techniques cannot be used. One example of this is when a program is getting data at a high rate from a real-time source, and cannot be slowed down or interrupted.
eCos's infrastructure module provides a tracing formalism, allowing the kernel's tracing macros to be configured in many useful ways. eCos's kernel provides instrumentation buffers which also collect specific (configurable) data about the system's history and performance.
To use eCos's tracing facilities you must first configure your system to use tracing. You should enable the Asserts and Tracing component ( CYGPKG_INFRA_DEBUG ) and the Use tracing component within it ( CYGDBG_USE_TRACING ). These options can be enabled with the Configuration Tool or by editing the file BUILD_DIR /pkgconf/infra.h manually.
You should then examine all the tracing-related options in the Package: Infrastructure chapter of the eCos Reference Manual. One useful set of configuration options are: CYGDBG_INFRA_DEBUG_FUNCTION_REPORTS and CYGDBG_INFRA_DEBUG_TRACE_MESSAGE, which are both enabled by default when tracing is enabled.
The following "Hello world with tracing" shows the output from running the hello world program (from the programming tutorial in Getting Started with eCos ) that was built with tracing enabled:
$ mips-tx39-elf-run --board=jmr3904 hello Hello, eCos world! ASSERT FAIL: <2>cyg_trac.h [ 623] Cyg_TraceFunction_Report_::set_exitvoid() exitvoid used in typed function TRACE: <1>mlqueue.cxx [ 395] Cyg_ThreadQueue_Implementation::enqueue() {{enter TRACE: <1>mlqueue.cxx [ 395] Cyg_ThreadQueue_Implementation::enqueue() }}RETURNING UNSET! TRACE: <1>mlqueue.cxx [ 126] Cyg_Scheduler_Implementation::add_thread() }}RETURNING UNSET! TRACE: <1>thread.cxx [ 654] Cyg_Thread::resume() }}return void TRACE: <1>cstartup.cxx [ 160] cyg_iso_c_start() }}return void TRACE: <1>startup.cxx [ 142] cyg_package_start() }}return void TRACE: <1>startup.cxx [ 150] cyg_user_start() {{enter TRACE: <1>startup.cxx [ 150] cyg_user_start() (((void))) TRACE: <1>startup.cxx [ 153] cyg_user_start() 'This is the system default cyg_user_start()' TRACE: <1>startup.cxx [ 157] cyg_user_start() }}return void TRACE: <1>sched.cxx [ 212] Cyg_Scheduler::start() {{enter TRACE: <1>mlqueue.cxx [ 102] Cyg_Scheduler_Implementation::schedule() {{enter TRACE: <1>mlqueue.cxx [ 437] Cyg_ThreadQueue_Implementation::highpri() {{enter TRACE: <1>mlqueue.cxx [ 437] Cyg_ThreadQueue_Implementation::highpri() }}RETURNING UNSET! TRACE: <1>mlqueue.cxx [ 102] Cyg_Scheduler_Implementation::schedule() }}RETURNING UNSET! TRACE: <2>intr.cxx [ 450] Cyg_Interrupt::enable_interrupts() {{enter TRACE: <2>intr.cxx [ 450] Cyg_Interrupt::enable_interrupts() }}RETURNING UNSET! TRACE: <2>thread.cxx [ 69] Cyg_HardwareThread::thread_entry() {{enter TRACE: <2>cstartup.cxx [ 127] invoke_main() {{enter TRACE: <2>cstartup.cxx [ 127] invoke_main() ((argument is ignored)) TRACE: <2>dummyxxmain.cxx [ 60] __main() {{enter TRACE: <2>dummyxxmain.cxx [ 60] __main() (((void))) TRACE: <2>dummyxxmain.cxx [ 63] __main() 'This is the system default __main()' TRACE: <2>dummyxxmain.cxx [ 67] __main() }}return void TRACE: <2>memcpy.c [ 112] _memcpy() {{enter TRACE: <2>memcpy.c [ 112] _memcpy() ((dst=80002804, src=BFC14E58, n=19)) TRACE: <2>memcpy.c [ 164] _memcpy() }}returning 80002804 TRACE: <2>cstartup.cxx [ 137] invoke_main() 'main() has returned with code 0. Calling exit()' TRACE: <2>exit.cxx [ 71] __libc_exit() {{enter TRACE: <2>exit.cxx [ 71] __libc_exit() ((status=0 )) TRACE: <2>atexit.cxx [ 84] cyg_libc_invoke_atexit_handlers() {{enter TRACE: <2>atexit.cxx [ 84] cyg_libc_invoke_atexit_handlers() (((void))) Scheduler: Lock: 0 Current Thread: <null> Threads: Idle Thread pri = 31 state = R id = 1 stack base = 800021F0 ptr = 80002510 size = 00000400 sleep reason NONE wake reason NONE queue = 80000C54 wait info = 00000000 <null> pri = 0 state = R id = 2 stack base = 80002A48 ptr = 8000A968 size = 00008000 sleep reason NONE wake reason NONE queue = 80000BD8 wait info = 00000000
Instrument buffers can be used to find out how many events of a given type happened in the kernel during execution of a program.
You can monitor a class of several types of events, or you can just look at individual events.
Examples of events that can be monitored are:
Examples of fine-grained scheduler event types are:
Information about the events is stored in an event record. The structure that defines this record has type struct Instrument_Record :
The list of records is stored in an array called instrument_buffer , which you can let the kernel provide or you can provide yourself by setting the configuration option CYGVAR_KERNEL_INSTRUMENT_EXTERNAL_BUFFER.
To write a program that examines the instrumentation buffers:
This program is also provided in the examples directory.
/* this is a program which uses eCos instrumentation buffers; it needs to be linked with a kernel which was compiled with support for instrumentation */ #include <stdio.h> #include <pkgconf/kernel.h> #include <cyg/kernel/instrmnt.h> #include <cyg/kernel/kapi.h> #ifndef CYGVAR_KERNEL_INSTRUMENT_EXTERNAL_BUFFER # error You must configure eCos with CYGVAR_KERNEL_INSTRUMENT_EXTERNAL_BUFFER #endif struct Instrument_Record { CYG_WORD16 type; // record type CYG_WORD16 thread; // current thread id CYG_WORD timestamp; // 32 bit timestamp CYG_WORD arg1; // first arg CYG_WORD arg2; // second arg }; struct Instrument_Record instrument_buffer[20]; cyg_uint32 instrument_buffer_size = 20; int main(void) { int i; cyg_instrument_enable(CYG_INSTRUMENT_CLASS_CLOCK, 0); cyg_instrument_enable(CYG_INSTRUMENT_CLASS_THREAD, 0); cyg_instrument_enable(CYG_INSTRUMENT_CLASS_ALARM, 0); printf("Program to play with instrumentation buffer\n"); cyg_thread_delay(2); cyg_instrument_disable(CYG_INSTRUMENT_CLASS_CLOCK, 0); cyg_instrument_disable(CYG_INSTRUMENT_CLASS_THREAD, 0); cyg_instrument_disable(CYG_INSTRUMENT_CLASS_ALARM, 0); for (i = 0; i < instrument_buffer_size; ++i) { printf("Record %02d: type 0x%04x, thread %d, ", i, instrument_buffer[i].type, instrument_buffer[i].thread); printf("time %5d, arg1 0x%08x, arg2 0x%08x\n", instrument_buffer[i].timestamp, instrument_buffer[i].arg1, instrument_buffer[i].arg2); } return 0; }
Here is how you could compile and run this program in the examples directory, using (for example) the MN10300 compiler:
$ make XCC=mn10300-elf-gcc PKG_INSTALL_DIR =/tmp/ecos-work-mn10300/install instrument-test mn10300-elf-gcc -c -o instrument-test.o -g -Wall -I/tmp/ecos-work-mn10300/install/include -ffunction-sections -fdata-sections instrument-test.c mn10300-elf-gcc -nostartfiles -L/tmp/ecos-work-mn10300/install/lib -W1,--gc-sections -o instrument-test instrument-test.o -Ttarget.ld -nostdlib $ mn10300-elf-run --board=stdeval1 instrument-test
Here is the output of the instrument-test program. Notice that in little over 2 seconds, and with very little activity, and with few event types enabled, it gathered 17 records. In larger programs it will be necessary to select very few event types for debugging.
Program to play with instrumentation buffer Record 00: type 0x0207, thread 2, time 6057, arg1 0x48001cd8, arg2 0x00000002 Record 01: type 0x0202, thread 2, time 6153, arg1 0x48001cd8, arg2 0x00000000 Record 02: type 0x0904, thread 2, time 6358, arg1 0x48001d24, arg2 0x00000000 Record 03: type 0x0905, thread 2, time 6424, arg1 0x00000002, arg2 0x00000000 Record 04: type 0x0906, thread 2, time 6490, arg1 0x00000000, arg2 0x00000000 Record 05: type 0x0901, thread 2, time 6608, arg1 0x48009d74, arg2 0x48001d24 Record 06: type 0x0201, thread 2, time 6804, arg1 0x48001cd8, arg2 0x480013e0 Record 07: type 0x0803, thread 1, time 94, arg1 0x00000000, arg2 0x00000000 Record 08: type 0x0801, thread 1, time 361, arg1 0x00000000, arg2 0x00000000 Record 09: type 0x0802, thread 1, time 548, arg1 0x00000001, arg2 0x00000000 Record 10: type 0x0803, thread 1, time 94, arg1 0x00000000, arg2 0x00000000 Record 11: type 0x0801, thread 1, time 361, arg1 0x00000001, arg2 0x00000000 Record 12: type 0x0903, thread 1, time 513, arg1 0x48009d74, arg2 0x48001d24 Record 13: type 0x0208, thread 1, time 588, arg1 0x00000000, arg2 0x00000000 Record 14: type 0x0203, thread 1, time 697, arg1 0x48001cd8, arg2 0x480013e0 Record 15: type 0x0802, thread 1, time 946, arg1 0x00000002, arg2 0x00000000 Record 16: type 0x0201, thread 1, time 1083, arg1 0x480013e0, arg2 0x48001cd8 Record 17: type 0x0000, thread 0, time 0, arg1 0x00000000, arg2 0x00000000 Record 18: type 0x0000, thread 0, time 0, arg1 0x00000000, arg2 0x00000000 Record 19: type 0x0000, thread 0, time 0, arg1 0x00000000, arg2 0x00000000
Debugging Techniques | ||
---|---|---|