Adding GDB BSPs to rtems-tester

[Gedare Bloom]

On Sun, Mar 22, 2020 at 1:40 AM Niteesh G. S. <niteesh.gs at gmail.com> wrote:
>
> I built mips jmr3904. I was able to run rtems-run and rtems-test on it.
> But cdtest.exe fails.
> *** TESTING C++ EXCEPTIONS ***
> mips-core: 1 byte read to unmapped address 0x2ed31 at 0x880290a4
> Program received signal SIGBUS, Bus error.
> 0x88028fe4 in strlen ()
> What is causing this error?
This shows that the strlen function is accessing a bad address
(0x2ed31). In fact, this is part of the value of the jmr3904 simulator
and why we want to get it working for routine testing, because it can
catch bad memory errors.

> I tried running this manually on GDB. On forcefully continuing.
The next step is not to forcefully continue, but to work backwards
from the failure in GDB. print a stack backtrace ('bt' command) to see
how it got to strlen. Look at the values of the registers you can
observe. Compare with the code in the example and trace the example
code forward along the path shown by the backtrace. Use GDB to
investigate the stack frames ('up' and 'down' commands).

> Warning, resuming with mismatched exception signal (7 vs 10)
After an unmapped address access, nothing else that executes is going
to be valid.

> Unhandled exception 7
> sr: 0x536936196  cause: 0x00029724 --> Data Bus Error
>
> *** FATAL ***
> fatal source: 1 (INTERNAL_ERROR_RTEMS_API)
> fatal code: 9800724312699699200 (0x100000000)
> RTEMS version: 5.0.0.37e7cc5f4ce7ed46b5ea2de56d9066d121d851cb-modified
> RTEMS tools: 7.5.0 20191114 (RTEMS 5, RSB 5 (0b7e87143b76), Newlib fbaa096)
> executing thread ID: 0x08a010001
> executing thread name: CTOR
>
> Is this problem with the BSP or simulator? And how can I fix this?

Most likely it is a problem with newlib.

>
> On Sat, Mar 21, 2020 at 11:33 PM Joel Sherrill <joel at rtems.org> wrote:
>>
>>
>>
>> On Sat, Mar 21, 2020 at 10:38 AM Niteesh G. S. <niteesh.gs at gmail.com> wrote:
>>>
>>> Which architecture should I try then? Maybe powerpc or mips? If you have any
>>> of them already built can you please try them out? Building everything from
>>> source takes a lot of time in my dev machine.
>>>
>>> On Sat, Mar 21, 2020 at 6:41 PM Gedare Bloom <gedare at rtems.org> wrote:
>>>>
>>>> On Sat, Mar 21, 2020 at 12:54 AM Niteesh G. S. <niteesh.gs at gmail.com> wrote:
>>>> >
>>>> > On Thu, Mar 19, 2020 at 11:43 PM Gedare Bloom <gedare at rtems.org> wrote:
>>>> >>
>>>> >> On Thu, Mar 19, 2020 at 11:56 AM Niteesh G. S. <niteesh.gs at gmail.com> wrote:
>>>> >> >
>>>> >> > Hello,
>>>> >> >
>>>> >> > While looking for small tasks to take up, Gedare mentioned about adding GDB BSPs
>>>> >> > to rtems-tester. Can some please explain a bit more of what has to be done? I guess
>>>> >> > we have to write configuration files for BSPs that support simulation in GDB. If so, how
>>>> >> > could I find those BSPs, do I have to individually look at all the BSPs?
>>>> >> >
>>>> >> As I said off-list, I don't know if there's a list of GDB BSPs, but I
>>>> >> know of at least:
>>>> >> powerpc/psim
>>>> >> mips/jmr3904
>>>> >> moxie/moxiesim
>>>> >> arm/gdbarmsim
>>>> >> sh/shsim
>>>> >>
>>>> >> I have no idea what any of their statuses are or if they are expected
>>>> >> to work. The first step would be building them and see if they run
>>>> >> anything. After that, you should look at the existing tester scripts for
>>>> >> some targets:
>>>> >>   rtems-tools.git/tester/rtems/testing/bsps
>>>> >> I see scripts for most of what I listed above, so the next step would
>>>> >> be trying to run them via tester and see if it works.
>>>> >
>>>> >
>>>> > I built the simsh1 BSP but couldn't get it running. Before trying it with rtems-run
>>>> > and rtems-test I tried manually loading it in the simulator. But gdb doesn't respond
>>>> > as soon as I execute the run command. The only way to exit it was using ctrl-c and GDB
>>>> > responds with
>>>> > sim_events_schedule_after_signal - buffer overflow
>>>> > Quit
>>>> > Aborted (core dumped)
>>>> > I tried setting breakpoints within GDB but it never seems to hit them. I tried running the
>>>> > examples through rtems-test results in ta imeout.
>>>> >
>>>> > Due to the slow internet connection and slow development machine, I could only build
>>>> > and test a few BSPs. In case if anyone has an already built tool suite and BSP for the
>>>> > mentioned arch please try them out.
>>>> >
>>>> I don't know that anyone uses this architecture. Don't spend too much
>>>> effort trying to debug the simulator :)
>>
>>
>> mips jmr3904 and powerpc psim should work well.
>>
>> I agree with Gedare, spending a lot of time on the SH isn't high payoff.
>> I'm glad for the report but there could be bitrot in the simulator or BSP.
>>
>>>>
>>>>
>>>> >> BTW: Did I mention adding these to tester, or did I mention creating
>>>> >> build sets for them? Anyway, I think the GDB simulator builds by
>>>> >> default with the toolchain, so there is no difference between a BSP
>>>> >> buildset (such as for jmr3904) and one that supports running on GDB.
>>>> >> At least, I think so. It is worth verifying.
>>>> >>
>>>> >> Gedare
>>>> >>
>>>> >> > Thank you,
>>>> >> > Niteesh.
>>>> >> > _______________________________________________
>>>> >> > devel mailing list
>>>> >> > devel at rtems.org
>>>> >> > http://lists.rtems.org/mailman/listinfo/devel