raspberry BSP: Maybe there is a bug in the linker file?

[Christian Mauderer]

On 21/12/2019 08:28, Niteesh wrote:
> Did you take a look at the exception?

Not yet.

> I still couldn't get it running on
> the rpi3 using rpi2 bsp.

Again: It's quite likely that the serial interface is a problem. I don't
think that you'll see any output on rpi3 without changes.

> I built the bsp again by checking out a commit before
> c5fd79cd4704a4270ba0114a1009ab8556f997c9
> and created a kernel.img using objcopy.

That should work. But Most likely you'll get your output on the serial
interface that is pointing to the bluetooth module.

> I tried running it on gdb with set scheduler-locking on. I seem to jump
> to bsp_vector_table_begin and hang there (0x000000c).

I thought you don't have a debugger connected? How do you run it with gdb?

> 
> 
> On Sat, Dec 21, 2019 at 1:42 AM Christian Mauderer <list at c-mauderer.de
> <mailto:list at c-mauderer.de>> wrote:
> 
>     On 20/12/2019 19:19, Niteesh wrote:
>     > How do you test a patch? Do you checkout that particular commit and
>     > build and the BSP again?.
> 
>     Basically yes: You check out the version that you want fixed and apply
>     the patch. In that case I have gone back and forward a few times to find
>     the commit that introduced the second bug.
> 
>     > @Christian Mauderer <mailto:list at c-mauderer.de
>     <mailto:list at c-mauderer.de>>  how did you build it
>     > for the rpi1? Did you follow the steps as in previous threads?
> 
>     Basically the same steps like for every BSP:
>     1. Build a recent toolchain using RSB.
>     2. Build the BSP.
>     3. Test it on the board.
> 
>     For the rpi1 the BSP is "raspberrypi" instead of "raspberrypi2". And I
>     didn't install the BSP because I only wanted the tests and no extra
>     application.
> 
>     For testing it I used the guide that you found: Objcopy into a binary
>     file and replace the kernel.img with it.
> 
>     > and how did you come to the conclusion that these changes cause the
>     > exceptions,
> 
>     I had a look at the history of the raspberry BSP (`gitk
>     bsps/arm/raspberrypi` or `git log bsps/arm/raspberrypi`) and looked for
>     suspicious patches. For the raspberry there are not much patches in the
>     last year so that was quite easy. Then I just tested before and after
>     some of the patches to find the ones that introduced the bugs.
> 
>     Again: In this case it was necessary to backport Sebastians patch so
>     that I have been able to test before / after the one that introduces the
>     exception.
> 
>     I haven't had a detailled look at the exception yet but I assume it's
>     some problem that the wrong variant is used or that my RPi1 is an early
>     model with less RAM or something like that.
> 
>     > as a beginner these ideas
>     > will help in the future.
>     > On Fri, Dec 20, 2019 at 2:46 PM Christian Mauderer
>     <list at c-mauderer.de <mailto:list at c-mauderer.de>
>     > <mailto:list at c-mauderer.de <mailto:list at c-mauderer.de>>> wrote:
>     >
>     >     On 20/12/2019 09:22, Christian Mauderer wrote:
>     >     > On 20/12/2019 07:33, Sebastian Huber wrote:
>     >     >> On 19/12/2019 15:28, Niteesh wrote:
>     >     >>> As far as I know, 0x8000 is a fixed address where the
>     bootloader
>     >     jumps
>     >     >>> to after loading the application assuming the CPU is in
>     32bit mode.
>     >     >>> For 64bit mode, it jumps to 0x80000.
>     >     >>
>     >     >> Would you mind testing this patch:
>     >     >>
>     >     >>
>     https://lists.rtems.org/pipermail/devel/2019-December/056551.html
>     >     >>
>     >     >
>     >     > On the Pi 1 now the binary has three time the size (with a
>     lot of 0x00
>     >     > in it) and at least RTEMS starts. But it runs into an
>     exception quite
>     >     > fast. I'll investigate that a bit.
>     >     >
>     >     > @Niteesh: For the Pi 3 I would expect that it still doesn't
>     print
>     >     > anything on the console due to the different UART pins.
>     >     >
>     >     > The output on the Pi 1 is:
>     >     >
>     >     > executing�
>     >     > *** FATAL ***
>     >     > fatal source: 9 (RTEMS_FATAL_SOURCE_EXCEPTION)
>     >     >
>     >     > R0   = 0xfc037f80 R8  = 0x00000000
>     >     > R1   = 0xfc345980 R9  = 0x00000010
>     >     > R2   = 0x00000001 R10 = 0xfc037f8a
>     >     > R3   = 0x03fc8080 R11 = 0x0030da00
>     >     > R4   = 0xfc037f80 R12 = 0xfc345988
>     >     > R5   = 0x00000008 SP  = 0x00300ba8
>     >     > R6   = 0x0030d9fe LR  = 0x00205a78
>     >     > R7   = 0x00305218 PC  = 0x00205ac8
>     >     > CPSR = 0x600001d3 VEC = 0x00000004
>     >     > RTEMS version: 5.0.0.254f38583fe68c3e17dfe274a2deeb00a5a538d6
>     >     > RTEMS tools: 7.5.0 20191114 (RTEMS 5, RSB 5 (6c65fc237b9e
>     modified),
>     >     > Newlib d14714c69)
>     >
>     >     The exception seems to be caused by some of the changes in
>     bspstart.c
>     >     and bspgetworkarea.c in patch
>     a4d7e4cee77d16b0e34ef543f0804e7eb2954137.
>     >     So the fix for the linker command file is fine.
>     >
>