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...@gmail.com> wrote:
> On Mon, Dec 16, 2019 at 2:36 AM Christian Mauderer <l...@c-mauderer.de> > wrote: > >> >> >> On 15/12/2019 21:29, Niteesh wrote: >> > >> > >> > On Mon, Dec 16, 2019 at 12:53 AM Christian Mauderer <l...@c-mauderer.de >> > <mailto:l...@c-mauderer.de>> wrote: >> > >> > On 15/12/2019 19:46, Niteesh wrote: >> > > >> > > >> > > On Sun, Dec 15, 2019 at 10:15 PM Christian Mauderer >> > <l...@c-mauderer.de <mailto:l...@c-mauderer.de> >> > > <mailto:l...@c-mauderer.de <mailto:l...@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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