Problem running RTEMS on raspberrypi3
Christian Mauderer
list at c-mauderer.de
Tue Dec 17 20:36:20 UTC 2019
That handler doesn't look like an RTEMS handler. So it failed at a very
early stage.
Did you try a go 0x200000 instead? Normally the first vector is a reset
vector which jumps to the right start address. The jump can have a mode
with it. So if you directly jump to 0x200080 the core might is in a
wrong mode.
On 16/12/2019 15:54, Niteesh wrote:
> What about using U-boot? I just tried running my own bare metal example
> using u-boot and it works fine.
> The 3rd stage bootloader start the u-boot and I was able to interact
> with it through serial. and then I used
> fatload mmc 0 0x8000 kernel.img ; go 0x8000
> to load and run the img. I tried the same for rtems
> fatload mmc 0 0x200000 rtems_kernel.img ; go 0x200080
> but this result's in a
>
> ## Starting application at 0x00200080 ...
> "Synchronous Abort" handler, esr 0x02000000
> elr: ffffffffc1d29080 lr : 00000000000838b0 (reloc)
> elr: 0000000000200080 lr : 000000003e55a8b0
> x0 : 0000000000000001 x1 : 000000003e15e6c8
> x2 : 000000003e15e6c8 x3 : 0000000000200080
> x4 : 0000000000000000 x5 : 0000000000000000
> x6 : 0000000000c0c0c0 x7 : 000000000000000f
> x8 : 00000000ffffffd0 x9 : 0000000000000008
> x10: 0000000000000010 x11: 000000003e159cc0
> x12: 0000000000000000 x13: 0000000000000200
> x14: 0000000000000005 x15: 0000000000000008
> x16: 0000000000000000 x17: 0000000000000020
> x18: 000000003e152de0 x19: 000000003e15e6c8
> x20: 0000000000000002 x21: 0000000000200080
> x22: 000000003e15e6c0 x23: 0000000000000002
> x24: 000000003e5d4d44 x25: 0000000000000000
> x26: 0000000000000000 x27: 0000000000000000
> x28: 000000003e1567e0 x29: 000000003e152b20
>
> Code: 0020b048 0020b048 0020b048 0020b048 (e1a05001)
> Resetting CPU ...
>
>
> On Mon, Dec 16, 2019 at 8:11 PM Niteesh <gsnb.gn at gmail.com
> <mailto:gsnb.gn at gmail.com>> wrote:
>
> But I am not able to boot using the 3 stage bootloader. Can someone
> try booting any examples on raspi3 or other newer models? If it's
> work's please
> post the instructions. The steps that I followed are:
> 1. arm-rtems5-objcopy -Obinary hello.exe kernel.img
> 2. copied the kernel image to sd card and modified the config.txt to
> load the kernel img.
> No success in following these steps.
> I think this is maybe because of the different start addresses. The
> default kernel load address for raspberry pi is 0x8000 in 32bit mode
> and 0x80000 in 64bit mode.
> but RTEMS has a start address of 0x200080.
>
>
> On Mon, Dec 16, 2019 at 7:51 PM Christian Mauderer
> <list at c-mauderer.de <mailto:list at c-mauderer.de>> wrote:
>
> I think I have guided you to a wrong path here. I mentioned U-Boot
> because it is often used on a lot of evaluation boards. In the
> raspberry
> case it seems that the stage 3 loader is something different. But
> everything should work with that stage 3 loader. I don't think that
> U-Boot is necessary.
>
> On 16/12/2019 14:01, Niteesh wrote:
> > I got uboot running on my raspi3. But I can't figure out to
> load and run
> > a custom kernel. Can you explain the steps or point me to some
> > reference.
> > On Mon, Dec 16, 2019 at 5:13 PM Niteesh <gsnb.gn at gmail.com
> <mailto:gsnb.gn at gmail.com>
> > <mailto:gsnb.gn at gmail.com <mailto:gsnb.gn at gmail.com>>> wrote:
> >
> > On Mon, Dec 16, 2019 at 2:36 AM 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 15/12/2019 21:29, Niteesh wrote:
> > >
> > >
> > > On Mon, Dec 16, 2019 at 12:53 AM 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>>
> > > <mailto: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 15/12/2019 19:46, Niteesh wrote:
> > > >
> > > >
> > > > On Sun, Dec 15, 2019 at 10:15 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>>
> > <mailto:list at c-mauderer.de <mailto:list at c-mauderer.de>
> <mailto:list at c-mauderer.de <mailto:list at c-mauderer.de>>>
> > > > <mailto:list at c-mauderer.de
> <mailto:list at c-mauderer.de> <mailto:list at c-mauderer.de
> <mailto:list at c-mauderer.de>>
> > <mailto:list at c-mauderer.de <mailto:list at c-mauderer.de>
> <mailto:list at c-mauderer.de <mailto:list at c-mauderer.de>>>>> wrote:
> > > >
> > > > Hello Niteesh,
> > > >
> > > > On 15/12/2019 09:05, Niteesh wrote:
> > > > > I am trying to get RTEMS examples
> running on the
> > RPI3, the
> > > RPI3 is
> > > > > similar to RPI2 so the examples built
> for RPI2 should
> > > technically
> > > > run on
> > > > > the RPi3.But they don't :(, I am really
> sure of
> > what is causing
> > > > the problem.
> > > >
> > > > Note that there are at least two different
> versions
> > of the
> > > RPi3 which
> > > > use different chips. The original RPi3
> which uses a
> > BCM2837
> > > (same like
> > > > later versions of RPi2) and the RPi3+
> which uses a
> > BCM2837B0.
> > > Broadcom
> > > > is always quite sparse with documentation
> so it's
> > not easy to
> > > tell the
> > > > differences. Which one do you have?
> > > >
> > > > I have Rpi3 model b v1.2 which uses BCM2837
> SOC, in my
> > bare-metal
> > > > programming I used the
> > > > 2835 doc as a reference because the only major
> > difference these
> > > two SOC
> > > > is the peripheral base address
> > > > offset. But this is arm cpu is also capable of
> > executing in 64bit
> > > mode.
> > >
> > > OK. Did you check, whether the offset is
> correct? In the
> > raspberrypi.h
> > > in RTEMS there is the following define:
> > >
> > > #if (BSP_IS_RPI2 == 1)
> > > #define RPI_PERIPHERAL_BASE 0x3F000000
> > > #else
> > > #define RPI_PERIPHERAL_BASE 0x20000000
> > > #endif
> > >
> > > The offsets are right.
> >
> > Good.
> >
> > >
> > > >
> > > > > I followed the steps
> > > > >
> > > >
> > >
> >
> from http://alanstechnotes.blogspot.com/2013/03/running-your-first-rtems-program-on.html (modified
> > > > > commands to use rtems5) to build the
> kernel img.
> > > >
> > > > It's a bit odd that the Bootloader doesn't
> use some
> > image
> > > format like
> > > > U-Boot but if that's the case for
> Raspberry, that's OK.
> > > >
> > > > Do you want me to try U-Boot, I was planning
> to use it
> > for my
> > > bare-metal
> > > > stuff because copying the kernel
> > > > to SD-card was a real pain. Will it even work
> with RTEMS?
> > >
> > > The manual that you linked uses the default
> Raspberry
> > bootloader. I'm
> > > not sure whether it's an U-Boot. If you skip the
> > bootloader entirely,
> > > your SDRAM might isn't initialized.
> > >
> > > The manual uses the default bootloader. I don't
> think we have
> > to worry
> > > about the SDRAM initialization
> > > because all of that is taken care of by the GPU.
> >
> > Sounds OK.
> >
> > > When using Uboot, the
> > > GPU will load the uboot image and
> > > pass the control to the CPU. And then the uboot
> continue's
> > it's execution.
> > >
> >
> > I don't wanted to suggest to use an extra U-Boot. I
> was just not
> > sure
> > whether the stage 3 loader is an U-Boot. Your approach
> sounds
> > fine so far.
> >
> > >
> > >
> > > PS: You answered that further below. You are
> using the
> > stage 3 loader.
> > >
> > > >
> > > > > I did try running it on
> > > > > Qemu but it doesn't always work,
> sometimes it gives
> > > weird output.
> > > >
> > > > How did you run it on Qemu? Did you build
> some image
> > for that too?
> > > >
> > > > qemu-system-arm -M raspi2 -m 1G -kernel hello.exe
> > -serial mon:stdio
> > > > -nographic
> > > > *
> > > > *
> > > > *
> > > > qemu-system-aarch64: GLib: g_mapped_file_unref:
> > assertion 'file !=
> > > NULL'
> > > > failed *I get this error
> > > > while trying to emulate raspi3.
> > >
> > > That sounds like a problem with Qemu. Is there some
> > official test image
> > > for rpi3 on qemu? Note that this isn't really
> relevant for
> > your current
> > > problem. So if you don't have some manual just
> ignore the
> > question.
> > >
> > > >
> > > > I ran qemu along with GDB to find what was
> causing the
> > wrong output. I
> > > > am really not sure if this is right,
> > > > I still have a lot to learn, but my
> assumption's using
> > GDB are as
> > > follows.
> > > > There are 4 active thread which run the same code.
> > > >
> > > > (gdb) info thread
> > > > Id Target Id Frame
> > > > * 1 Thread 1.1 (CPU#0 [running]) _start
> () at
> > > >
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/shared/start/start.S:153
> > > > 2 Thread 1.2 (CPU#1 [running]) _start
> () at
> > > >
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/shared/start/start.S:153
> > > > 3 Thread 1.3 (CPU#2 [running]) _start
> () at
> > > >
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/shared/start/start.S:153
> > > > 4 Thread 1.4 (CPU#3 [running]) _start
> () at
> > > >
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/shared/start/start.S:153
> > >
> > > In this case that are not threads but it's the
> CPU cores.
> > GDB shows them
> > > as threads. Most likely it wouldn't be able to
> detect the
> > RTEMS threads.
> > >
> > > It's a bit odd that they are all pointing to
> start.S:153.
> > That's the
> > > entry point for the program. It looks like not
> even one
> > instruction has
> > > been executed yet.
> > >
> > > I took this output before executing the program,
> that the
> > reason why not
> > > even a single instruction has been
> > > executed yet.
> >
> > OK.
> >
> > >
> > > >
> > > > After some time one of the thread call's the
> BSP reset
> > function
> > > this is
> > > > when the program crashes, the other threads
> complain
> > "*executing
> > > thread
> > > > is NULL*"
> > >
> > > I would rather assume that one core tries to do the
> > initialization while
> > > the others hang in a endless loop till they are
> needed.
> > The one core
> > > doing the initialization work hits an exception
> somewhere
> > and calls the
> > > exception handler which calls the bsp reset
> function.
> > >
> > > The executing thread is NULL is a sign that it
> happens
> > somewhere during
> > > initialization when the RTEMS threading hasn't been
> > started yet.
> > >
> > > The PC has an odd value. The linker command file
> tells
> > that there is a
> > > RAM_MMU at 0x00100000. It only puts a
> > bsp_translation_table there but
> > > there shouldn't be any code. So I don't know
> what the
> > processor is doing
> > > there. You could try to set a breakpoint on the
> address
> > 0x00100fc4 and
> > > take a look at why the processor is there with a
> "bt"
> > (backtrace).
> > >
> > > When I re-run it again, it now stops at a different
> address.
> > As you said
> > > that the other cores are put
> > > in an endless loop, I don't think that's is happening. I
> > single stepped
> > > the instruction and later at some point checked the
> threads
> > >
> > > (gdb) info threads
>
> >
> > >
>
> >
> > >
>
> > > Target Id Frame
> > > 1 Thread 1.1 (CPU#0 [running])
> arm_ccsidr_get_line_power
> > > (ccsidr=<optimized out>)
> > > at
> > >
> >
> /home/niteesh/development/rtems/kernel/rtems/cpukit/score/cpu/arm/include/libcpu/arm-cp15.h:850
> > > 2 Thread 1.2 (CPU#1 [running])
> > arm_cp15_cache_invalidate_level
> > > (inst_data_fl=0, level=1)
> > > at
> > >
> >
> /home/niteesh/development/rtems/kernel/rtems/cpukit/score/cpu/arm/include/libcpu/arm-cp15.h:1162
> > > 3 Thread 1.3 (CPU#2 [running])
> arm_ccsidr_get_line_power
> > > (ccsidr=<optimized out>)
> > > at
> > >
> >
> /home/niteesh/development/rtems/kernel/rtems/cpukit/score/cpu/arm/include/libcpu/arm-cp15.h:850
> > > * 4 Thread 1.4 (CPU#3 [running])
> > > arm_cp15_get_cache_size_id_for_level
> (level_and_inst_dat=0)
> > > at
> > >
> >
> /home/niteesh/development/rtems/kernel/rtems/cpukit/score/cpu/arm/include/libcpu/arm-cp15.h:936
> > > (gdb)
> > >
> > > They all are executing different instructions at the
> same time.
> >
> > Some of the initialization is done on all cores. Some
> isn't. I
> > took a
> > look at the initialization and it seems that I was
> wrong: There
> > is no
> > wait loop. All processors are running through the
> initialization
> > process. Some just skip parts. The part where they
> really start to
> > differ is in bsp_start_hook_0.
> >
> > > I> googled about just running one thread or CPU as
> you said at
> > a time and
> > > used "*set scheduler-locking on" *on doing this I
> always get
> > the right
> > > output.
> > >
> > > (gdb) info threads
> > > Id Target Id Frame
> > > * 1 Thread 1.1 (CPU#0 [running]) bsp_reset ()
> > > at
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/raspberrypi/start/bspreset.c:18
> > > 2 Thread 1.2 (CPU#1 [running]) _start ()
> > > at
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/shared/start/start.S:153
> > > 3 Thread 1.3 (CPU#2 [running]) _start ()
> > > at
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/shared/start/start.S:153
> > > 4 Thread 1.4 (CPU#3 [running]) _start ()
> > > at
> > >
> >
> ../../../../../../../../rtems/c/src/lib/libbsp/arm/raspberrypi/../../../../../../bsps/arm/shared/start/start.S:153
> > > (gdb)
> > >
> > > The above command allow's only a single thread to run.
> >
> > Maybe there is a timing difference between the
> simulator and the
> > real
> > hardware. I'm not sure how well tested the SMP code is
> on the
> > Raspberry.
> > There can be a hidden bug.
> >
> > Just a guess: If there is a bug it could be possible
> that you hit it
> > with your rpi3 too. Maybe it would be good to try a
> single core
> > version
> > of the BSP. I assume you have configured with
> "--enable-smp"?
> > Can you
> > try to build without it?
> >
> > I built 2 versions with SMP enabled and disabled, the one
> we are
> > talking about is the SMP disabled version, I ran
> > the example with SMP enabled, still, the error's are
> similar, I only
> > difference is, in the disabled one, there are only 4 or
> less panic's
> > (maybe corresponding to 4 cpu's) but the other one has a
> higher
> > number of panics.
> >
> > > Won't it be a good idea to make a separate BSP for rpi3?
> >
> > As soon as it is necessary: Sure. But from what you
> told me it seems
> > that the hardware is very similar so that we won't hit
> this
> > point soon.
> > Or do you already see differences that would make it
> necessary.
> >
> > I haven't had a look at the details but it could also
> be possible to
> > unify the BSPs and entirely remove the rpi2 variant if the
> > information
> > from the flattened device tree are used.
> >
> > Can you explain how FDT work in RTEMS. Can you mention
> some BSP's
> > which use FDT so I can use them as a reference to learn.
> > I previously took a look at the beagle FDT project
> (#3784), you
> > mentioned about hardcoded values and initialization
> functions, can
> > you explain more about what exactly do the initialization
> functions
> > do? Do they assign a function to a particular pin, like in
> raspi
> > the pins are multiplexed for various functions, so do the
> > initialization functions assign those pins to a particular
> function?
> >
> > And also please explain how does the initialization of the
> system
> > happen from the DT file.
> >
> > >
> > > > *** FATAL ***
> > > > fatal source: 9 (RTEMS_FATAL_SOURCE_EXCEPTION)
> > > >
> > > > R0 = 0x400005e6 R8 = 0x00000000
> > > > R1 = 0x00000001 R9 = 0x00000000
> > > > R2 = 0xbffffa1a R10 = 0x00000000
> > > > R3 = 0x00000000 R11 = 0x00000000
> > > > R4 = 0x002001db R12 = 0x00000000
> > > > R5 = 0x00000000 SP = 0x00300bd0
> > > > R6 = 0x00000000 LR = 0x00100fc4
> > > > R7 = 0x00000000 PC = 0x00100fc4
> > > > CPSR = 0x000001d3 VEC = 0x00000002
> > > > FPEXC = 0x40000000
> > > > FPSCR = 0x00000000
> > > > D00 = 0x0000000000000000
> > > > D01 = 0x0000000000000000
> > > > D02 = 0x0000000000000000
> > > > D03 = 0x0000000000000000
> > > > D04 = 0x0000000000000000
> > > > D05 = 0x0000000000000000
> > > > D06 = 0x0000000000000000
> > > > D07 = 0x0000000000000000
> > > > D08 = 0x0000000000000000
> > > > D09 = 0x0000000000000000
> > > > D10 = 0x0000000000000000
> > > > D11 = 0x0000000000000000
> > > > D12 = 0x0000000000000000
> > > > D13 = 0x0000000000000000
> > > > D14 = 0x0000000000000000
> > > > D15 = 0x0000000000000000
> > > > D16 = 0x0000000000000000
> > > > D17 = 0x0000000000000010
> > > > D18 = 0x0000000000000000
> > > > D19 = 0x0000000000000000
> > > > D20 = 0x0000000000000000
> > > > D21 = 0x0000000000000000
> > > > D22 = 0x0000000000000000
> > > > D23 = 0x0000000000000000
> > > > D24 = 0x0000000000000000
> > > > D25 = 0x0000000000000000
> > > > D26 = 0x0000000000000000
> > > > D27 = 0x0000000000000000
> > > > D28 = 0x0000000000000000
> > > > D29 = 0x0000000000000000
> > > > D30 = 0x0000000000000000
> > > > D31 = 0x0000000000000000
> > > > RTEMS version:
> > >
> 5.0.0.c6d8589bb00a9d2a5a094c68c90290df1dc44807-modified
> > > > RTEMS tools: 7.5.0 20191114 (RTEMS 5, RSB
> > > > 83fa79314dd87c0a8c78fd642b2cea3138be8dd6,
> Newlib
> > 3e24fbf6f)
> > > > executing thread is NULL
> > > >
> > > > > The steps that I followed are:
> > > > > 1. Created a bootable SD card using
> raspbian.
> > > > > 2. Replaced the kernel.img file with RTEMS
> > kernel.img file and
> > > > modified
> > > > > the config.txt to boot from the RTEMs
> kernel (boots in
> > > aarch32 bit
> > > > mode).
> > > > > I am still not able to wrap my head
> around the RPI
> > bsp build
> > > process.
> > > > > This is what I understood as of now,
> correct me if
> > I am wrong.
> > > > > Both RPi and Rpi2 are based on the same
> BSP, they just
> > > differ in the
> > > > > peripheral offsets, hardcoded checks are
> used to
> > select the
> > > right
> > > > offset
> > > > > at the time of compiling
> > > >
> > > > >From what I know of the Raspberry BSPs
> that is correct.
> > > >
> > > > > and the linkercmd file is responsible for
> > > > > building the final executable file.
> > > >
> > > > The linkercmd file is - like for all
> programs -
> > responsible
> > > where the
> > > > memory regions are that can be used for
> code or
> > data. So you
> > > could more
> > > > or less explain it like you did.
> > > >
> > > > > I looked at the linker script, it seem's
> to have
> > the start
> > > section at
> > > > > address 0x200000, I also loaded it in
> GDB and the
> > start
> > > address is
> > > > > *Start address 0x200080,*
> > > >
> > > > I agree with that. The different start in
> GDB is
> > most likely
> > > because
> > > > there is a vector table in front (at least
> if the
> > Broadcom chip is
> > > > similar to a lot of other processors that
> I have
> > encountered).
> > > >
> > > > Does that mean that you have a debugger
> connected to the
> > > raspberry? Can
> > > > you load code with it? If yes: Is the
> bootloader
> > executed
> > > before you
> > > > load your code? Otherwise the SDRAM might
> isn't
> > initialized yet.
> > > >
> > > > I don't have a debugger connected to it. I
> from what I
> > have SDRAM is
> > > > initialized by the 3 stage bootloader(start.elf).
> > >
> > > That should be OK and it answers my question above.
> > >
> > > >
> > > > > I did some bare metal programming on RPI3
> > > > > there I had the start section at address
> 0x8000 Is
> > this causing
> > > > the problem?
> > > >
> > > > I assume that you used some internal RAM
> when you
> > did bare metal
> > > > programming. You maybe even skipped one or two
> > bootloader
> > > stages. From a
> > > > quick look Raspberry has a quite complex boot
> > process with at
> > > least
> > > > three bootloaders:
> > > http://lions-wing.net/maker/raspberry-1/boot.html
> > > >
> > > > I don't think I have skipped any stages. The
> boot process is
> > > exactly the
> > > > same as how it boot's a normal raspbian or any
> other linux
> > > > distro, I just to replace the linux kernel
> with my own
> > kernel.
> > >
> > > Sounds reasonable. Does the bootloader print
> anything
> > where it puts the
> > > kernel image? Maybe the start address changed
> during the
> > raspberry
> > > versions.
> > >
> > > the default kernel load address is 0x8000 in 32bit
> mode and
> > 0x80000 in
> > > 64bit mode I have no idea about the raspberry 1,
> > > but the load address is same for rpi2 and 3.
> >
> > That sounds odd. Do you have a memory map somewhere?
> From the linker
> > command file it seems quite clear that RTEMS is build
> for a
> > 0x200000.
> >
> > >
> > > >
> > > >
> > > > > I have no idea on how to debug this, any
> > suggestion on how
> > > to start
> > > > > would be really helpfull.
> > > > >
> > > >
> > >
> >
>
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