Will keep this in mind. Thanks.
On Thu, Jul 2, 2020 at 4:05 PM Jiri Gaisler <jiri at gaisler.se> wrote:
> Note that single-stepping of smp code at instruction-level might affect
> the timing of the execution. During single-stepping, only one core is
> advanced while the others stay halted. If you are trying to catch a race
> condition then the timing impact might change the program behavior. Shorter
> bursts of single-stepping will usually not have any side-effect as the
> default execution slot for each cpu is 50 clocks, but it might be good be
> aware of this behavior ...
>
> Jiri.
> On 7/2/20 10:32 AM, Richi Dubey wrote:
>
> Yeah, this makes a lot of sense.
> Mr. Huber also told me a similar story about qemu using -O0 optimizations
> which are easier to debug.
>
> Thank you.
>
> On Wed, Jul 1, 2020 at 8:03 PM Gedare Bloom <gedare at rtems.org> wrote:
>
>> On Wed, Jul 1, 2020 at 5:32 AM Richi Dubey <richidubey at gmail.com> wrote:
>> >
>> > Dear Dr. Gaisler,
>> >
>> > There's something that I am getting stuck at while trying to debug an
>> smp03 (https://git.rtems.org/rtems/tree/testsuites/smptests/smp03/init.c)
>> test suite with gdb running on sis.
>> >
>> > I started sis with the command:
>> >
>> -------------------------------------------------------------------------------------------------------------------
>> >
>> > $ ./sparc-rtems5-sis -leon3 -m 4 -gdb
>> >
>> > SIS - SPARC/RISCV instruction simulator 2.21, copyright Jiri Gaisler
>> 2019
>> > Bug-reports to jiri at gaisler.se
>> >
>> > LEON3 emulation enabled, 4 cpus online, delta 50 clocks
>> >
>> > gdb: listening on port 1234
>> >
>> -------------------------------------------------------------------------------------------------------------------
>> > and gdb with the command:
>> >
>> >
>> -------------------------------------------------------------------------------------------------------------------
>> > $ ./sparc-rtems5-gdb
>> ~/quick-start/build/b-smp-leon3/sparc-rtems5/c/leon3/testsuites/smptests/smp03.exe
>> > .
>> > .
>> > .
>> > Reading symbols from
>> /home/richi/quick-start/build/b-smp-leon3/sparc-rtems5/c/leon3/testsuites/smptests/smp03.exe...
>> > (gdb) target extended-remote localhost:1234
>> > Remote debugging using localhost:1234
>> > 0x00000000 in ?? ()
>> > (gdb) load
>> > Loading section .text, size 0x20440 lma 0x40000000
>> > Loading section .rtemsroset, size 0x90 lma 0x40020440
>> > Loading section .data, size 0x690 lma 0x40028500
>> > Start address 0x40000000, load size 133984
>> > Transfer rate: 1063 KB/sec, 271 bytes/write.
>> > (gdb) b _Scheduler_EDF_SMP_Get_highest_ready
>> > Breakpoint 1 at 0x4000e620: _Scheduler_EDF_SMP_Get_highest_ready. (4
>> locations)
>> > (gdb) continue
>> > Continuing.
>> >
>> > Breakpoint 1, _Scheduler_EDF_SMP_Get_highest_ready (filter=0x40029000
>> <_RTEMS_tasks_Objects+576>,
>> > context=0x4002bc28 <_Configuration_Scheduler_EDF_SMP_dflt>)
>> > at
>> /home/richi/quick-start/src/rtems/c/src/../../cpukit/score/src/scheduleredfsmp.c:151
>> > 151 self = _Scheduler_EDF_SMP_Get_self( context );
>> > (gdb) stepi
>> > 0x4000e624 151 self = _Scheduler_EDF_SMP_Get_self( context );
>> > (gdb) stepi
>> > RBTree_Control_RB_MINMAX (val=-1, head=head at entry=0x4002bc74
>> <_Configuration_Scheduler_EDF_SMP_dflt+76>)
>> > at
>> /home/richi/quick-start/src/rtems/c/src/../../cpukit/score/src/rbtreenext.c:37
>> > 37 {
>> > (gdb) stepi
>> > 0x4001787c 37 {
>> > (gdb) stepi
>> > 0x40017880 37 {
>> > (gdb) stepi
>> > 0x40017884 37 {
>> > (gdb) stepi
>> > 0x40017890 37 {
>> > (gdb) stepi
>> > 0x40017894 37 {
>> > (gdb) stepi
>> > _RBTree_Minimum (tree=tree at entry=0x4002bc74
>> <_Configuration_Scheduler_EDF_SMP_dflt+76>)
>> > at
>> /home/richi/quick-start/src/rtems/c/src/../../cpukit/score/src/rbtreenext.c:39
>> > 39 }
>> > (gdb) stepi
>> > 0x400178a0 39 }
>> > (gdb) stepi
>> > 0x400178a4 39 }
>> > (gdb) stepi
>> > 0x400178a8 39 }
>> > (gdb) stepi
>> > 0x4000e628 in _Scheduler_EDF_SMP_Get_highest_ready (filter=0x40029000
>> <_RTEMS_tasks_Objects+576>,
>> > context=0x4002bc28 <_Configuration_Scheduler_EDF_SMP_dflt>)
>> > at
>> /home/richi/quick-start/src/rtems/c/src/../../cpukit/score/src/scheduleredfsmp.c:151
>> > 151 self = _Scheduler_EDF_SMP_Get_self( context );
>> > (gdb) stepi
>> > 164
>> > (gdb) stepi
>> > 0x4000e630 164
>> > (gdb) stepi
>> > 0x4000e634 164
>> > (gdb) stepi
>> > 0x4000e638 164
>> > (gdb) stepi
>> > 175
>> > (gdb) stepi
>> > 0x4000e694 175
>> > (gdb)
>> >
>> -------------------------------------------------------------------------------------------------------------------
>> > Now I can't figure out why gdb won't show me the next instruction after
>> 151 self = _Scheduler_EDF_SMP_Get_self( context );? Why is it jumping to
>> instruction 164 and later to 175? What might be going wrong? Please let me
>> know.
>> >
>>
>> This can happen because of compiler optimizations. The order of the
>> assembly instructions in the program does not need to match exactly
>> the order in the source code, and some source lines might not have any
>> assembly associated with them. You can turn off optimization, or you
>> can compare the debug execution with the assembly program, to try to
>> get some more insight.
>>
>> > Thanks,
>> > Richi.
>> >
>> > On Fri, May 29, 2020 at 12:55 PM Richi Dubey <richidubey at gmail.com>
>> wrote:
>> >>
>> >> Thanks a lot! It is working now after I set appropriate breakpoints.
>> >>
>> >> On Tue, May 26, 2020 at 11:58 PM Jiri Gaisler <jiri at gaisler.se> wrote:
>> >> >
>> >> >
>> >> > On 5/26/20 2:55 PM, Richi Dubey wrote:
>> >> > > Hii,
>> >> > >
>> >> > > Thank you for your replies. I did not load the program before
>> >> > > executing run on gdb. Now it works fine.
>> >> > >
>> >> > > However, I need your help with one more thing. When I run gdb with
>> >> > > stepi or nexti to see how the code runs from the beginning to the
>> end,
>> >> > > gdb always ends up going in an infinite loop in hard_reset () at
>> >> > >
>> /home/richi/quick-start/src/rtems/c/src/lib/libbsp/sparc/leon3/../../../../../../bsps/sparc/shared/start/start.S:274
>> >> > > while only executing the following commands:
>> >> > >
>> >> > > 371 std %g0,[%g2]
>> >> > > (gdb)
>> >> > > 372 add %g2,8,%g2
>> >> > > (gdb)
>> >> > > 373 cmp %g2,%g3
>> >> > > (gdb)
>> >> > > 374 bleu,a zerobss
>> >> > > (gdb)
>> >> > > 375 nop
>> >> > >
>> >> > >
>> >> > > while the code in start.s is:
>> >> > >
>> >> > > zerobss:
>> >> > > std %g0,[%g2]
>> >> > > add %g2,8,%g2
>> >> > > cmp %g2,%g3
>> >> > > bleu,a zerobss
>> >> > > nop
>> >> > >
>> >> > > ---------------------
>> >> > >
>> >> > > Can someone please tell me why gdb is not going back to the main
>> file
>> >> > > smpschededf02/init.c? Is it because we keep running start.s during
>> the
>> >> > > entire time of execution?
>> >> >
>> >> > zerobss: function is not infinite, it just loops for many thousands
>> (millions) iterations while it clears the bss segment. SIngle-stepping
>> though zerobss: will obviously take a VERY long time, so put a breakpoint
>> on somewhere after it has been called.
>> >> >
>> >> >
>> >> > > And how do I run gdb while going through
>> >> > > every instruction that init.c processes without getting stuck in an
>> >> > > infinite loop like this. I set up a breakpoint at Init and
>> everythings
>> >> > > work fine but I am stilling missing the commands that were executed
>> >> > > before Init.c was called. How do I see those?
>> >> > >
>> >> > > Also, If I use step with breakpoint at Init, it again goes into an
>> >> > > infinite loop inside apbuart_polled.c with the following commands:
>> >> > >
>> >> > > 20 while ( (regs->status & APBUART_STATUS_TE) == 0 ) {
>> >> > > (gdb)
>> >> > > 22 __asm__ volatile ("nop"::); __asm__ volatile ("nop"::);
>> >> > > (gdb)
>> >> > > 23 __asm__ volatile ("nop"::); __asm__ volatile ("nop"::);
>> >> > > (gdb)
>> >> > > 24 __asm__ volatile ("nop"::); __asm__ volatile ("nop"::);
>> >> > > (gdb)
>> >> > > 25 __asm__ volatile ("nop"::); __asm__ volatile ("nop"::);
>> >> > >
>> >> > > Why is it running into an infinite loop?(If I use nexti, it does
>> not
>> >> > > run into an infinite loop as next does get inside functions, and
>> Init
>> >> > > finishes successfully).
>> >> >
>> >> > The loop is not infinite, it just loops while waiting for the UART
>> transmitter to send out a character. nexti puts a breakpoint after the
>> loop, that is why it finishes.
>> >> >
>> >> > Jiri.
>> >> >
>> >> >
>> >> > >
>> >> > > Thanks,
>> >> > > Richi.
>> >> > >
>> >> > > On Tue, May 26, 2020 at 12:44 AM Jiri Gaisler <jiri at gaisler.se>
>> wrote:
>> >> > >>
>> >> > >> On 5/25/20 4:30 PM, Richi Dubey wrote:
>> >> > >>> Hii everyone,
>> >> > >>>
>> >> > >>> When I am executing smpschededf02.exe on my leon3 bsp running on
>> >> > >>> sparc5 with sparc-rtems5-sis with -m 4 -leon3 option, it fails
>> to
>> >> > >>> execute properly.
>> >> > >>>
>> >> > >>> I have built leon3 with --enable-smp option and I am guessing the
>> >> > >>> execution fails because I don not see any output of the test and
>> I can
>> >> > >>> only see the following output:
>> >> > >>> ---------------------------------------------
>> >> > >>> ~/quick-start/rtems/5/bin$ ./sparc-rtems5-sis -leon3 -m 4
>> >> > >>>
>> ~/quick-start/build/leon3/sparc-rtems5/c/leon3/testsuites/smptests/smpschededf02.exe
>> >> > >>>
>> >> > >>> SIS - SPARC/RISCV instruction simulator 2.21, copyright Jiri
>> Gaisler 2019
>> >> > >>> Bug-reports to jiri at gaisler.se
>> >> > >>>
>> >> > >>> LEON3 emulation enabled, 4 cpus online, delta 50 clocks
>> >> > >>>
>> >> > >>> Loaded
>> /home/richi/quick-start/build/leon3/sparc-rtems5/c/leon3/testsuites/smptests/smpschededf02.exe,
>> >> > >>> entry 0x40000000
>> >> > >>> cpu0> run
>> >> > >>>
>> >> > >>>
>> >> > >>> *** BEGIN OF TEST SMPSCHEDEDF 2 ***
>> >> > >>> *** TEST VERSION: 5.0.0.20a8361de4724658112ecd33c28fae82a15919f8
>> >> > >>> *** TEST STATE: EXPECTED_PASS
>> >> > >>> *** TEST BUILD: RTEMS_NETWORKING RTEMS_POSIX_API RTEMS_SMP
>> >> > >>> *** TEST TOOLS: 7.5.0 20191114 (RTEMS 5, RSB 5 (0b7e87143b76),
>> Newlib fbaa096)
>> >> > >>>
>> >> > >>> *** END OF TEST SMPSCHEDEDF 2 ***
>> >> > >>>
>> >> > >>> cpu 1 in error mode (tt = 0x80)
>> >> > >>> 3491850 40016360: 91d02000 ta 0x0
>> >> > >>> -------------------------------------------------------
>> >> > >> Looks good to me, test passed OK and processor is halted by RTEMS.
>> >> > >>
>> >> > >>
>> >> > >>> On running the program with gdb with extended-remote and
>> debugging
>> >> > >>> with sis, I am encountering the following error:
>> >> > >>>
>> >> > >>> ----------------------
>> >> > >>> (gdb) target extended-remote localhost:1234
>> >> > >>> Remote debugging using localhost:1234
>> >> > >>> 0x00000000 in ?? ()
>> >> > >>> (gdb)
>> >> > >>> ------------------------
>> >> > >> This is indeed how you start remote debugging, but then you also
>> have to do:
>> >> > >>
>> >> > >> load
>> >> > >>
>> >> > >> run
>> >> > >>
>> >> > >> Then the program should run as expected ...
>> >> > >>
>> >> > >>
>> >> > >> Jiri.
>> >> > >>
>> >> > >>
>> >> > >> _______________________________________________
>> >> > >> devel mailing list
>> >> > >> devel at rtems.org
>> >> > >> http://lists.rtems.org/mailman/listinfo/devel
>> >> >
>> >
>> > _______________________________________________
>> > devel mailing list
>> > devel at rtems.org
>> > http://lists.rtems.org/mailman/listinfo/devel
>>
>
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