Loading RTEMS-application with U-boot on Raspberry Pi

[Jan Sommer]

Am Wednesday 13 April 2016, 11:50:15 schrieb Chris Johns:
[...]
> >> You have to specify the correct entry and load addresses for the
> >> mkimage.  For example:
> >>
> >
> > Ok. If I try to follow that procedure, I have:
> > readelf -l  blinker-rtems.exe
> > Elf file type is EXEC (Executable file)
> > Entry point 0x8040
> > There are 4 program headers, starting at offset 52
> >
> > Program Headers:
> >    Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
> >    EXIDX          0x010014 0x00100c54 0x00100c54 0x00008 0x00008 R   0x4
> >    LOAD           0x0000b4 0x00000000 0x00000000 0x00000 0x01440 RW  0x1
> >    LOAD           0x0000b4 0x00008000 0x00008000 0x0f300 0xf8000 RWE 0x4
> >    LOAD           0x00f3c0 0x00100000 0x00100000 0x01280 0x7efc000 RW  0x20
> 
> The significant sizes are 0x0f300 + 0x01280 which is about 66K.
> 

Hm, the binary file (created with arm-rtems4.12-objcopy) is 996K.

> >
> >   Section to Segment mapping:
> >    Segment Sections...
> >     00     .ARM.exidx
> >     01     .vector
> >     02     .start .text .init .fini .robarrier
> >     03     .rodata .ARM.exidx .eh_frame .init_array .fini_array .jcr .rtemsroset .data .bss .work
> >
> > .start is in section 02, hence my load address would be 0x8000 and the entry point is 0x8040 (I hope I got that right?).
> > If I create my image using:
> > mkimage -A arm -O rtems -T standalone -C none -a 0x8000 -e 0x8040 -d blinker-rtems.exe  blinker-rtems.img
> > And load it via u-boot with
> > fatload mmc 0:1 ${kernel_addr_r} blinker-rtems.img
> > bootm ${kernel_addr_r}
> >
> > It either hangs after Transferring control to RTEMS or resets with:
> > ## Booting kernel from Legacy Image at 01000000 ...
> 
> Why 01000000? when the lowest address above is 0x00008000?
> 

That should be the load address for the uboot image created with mkimage. If I understand the uboot process correctly u-boot will read the image header, unpack (if necessary) and copy the file to the specified address and transfer control to the loaded program.
The load address (below) is given as 0x8000.

> >
> >     Image Name:   blinker1
> >
> >     Image Type:   ARM RTEMS Standalone Program (uncompressed)
> >
> >     Data Size:    3494208 Bytes = 3.3 MiB
> 
> What is the 3.3M being loaded?
> 

It was my mistake. I packed the elf-file into the mkimage at first and not the binary file.
Now it's 996K which are loaded. Not sure why it is so much more then the 66k you mentioned.

> >
> >     Load Address: 00008000
> >
> >     Entry Point:  00008040
> >
> >     Verifying Checksum ... OK
> >
> >     Loading Standalone Program ... OK
> >
> > ## Transferring control to RTEMS (at address 00008040) ...
> >
> > data abort
> >
> > pc : [<19273304>]\0x09   lr : [<1bf59eb0>]
> >
> > reloc pc : [<fd330304>]\0x09   lr : [<00016eb0>]
> 
> What is at 00016eb0?

It was probably a problem related to me packing the elf file.
The data abort does not occur anymore. However, the program still gets stuck after
" ## Transferring control to RTEMS (at address 00008040)".

Best regards

   Jan

> 
> Chris
> 
> >
> > sp : 1bb46c00  ip : 00000520\0x09 fp : 1bf59e84
> >
> > r10: 00000000  r9 : 1bb46ee8\0x09 r8 : 400001d3
> >
> > r7 : 1bb475bc  r6 : 1bf59e84\0x09 r5 : 1bf912bc  r4 : 00000000
> >
> > r3 : 00000002  r2 : 00000000\0x09 r1 : 00000000  r0 : 400001d3
> >
> > Flags: nZcv  IRQs off  FIQs off  Mode SVC_32
> >
> > Resetting CPU ...
> >
> > resetting ...
> >
> > Again, if I follow the same procedure with the simple bare metal application, it works.
> >
> > Best regards,
> >
> >     Jan
> >
> >> readelf -l ticker.exe
> >>
> >> Elf file type is EXEC (Executable file)
> >> Entry point 0x400145
> >> There are 5 program headers, starting at offset 52
> >>
> >> Program Headers:
> >>     Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
> >>     EXIDX          0x00ec70 0x0040eb70 0x0040eb70 0x00008 0x00008 R 0x4
> >>     LOAD           0x000100 0x00400000 0x00400000 0x0ebc4 0x0ebc4 RWE 0x40
> >>     LOAD           0x00ecc8 0x20401148 0x0040ebc4 0x006a4 0x006a4 RW 0x8
> >>     LOAD           0x00f380 0x20400000 0x20400000 0x00000 0x5f000 RW 0x20
> >>     LOAD           0x00f36c 0x2045f000 0x2045f000 0x00000 0x01000 RW 0x1
> >>
> >>    Section to Segment mapping:
> >>     Segment Sections...
> >>      00     .ARM.exidx
> >>      01     .start .text .init .fini .rodata .ARM.exidx .eh_frame
> >> .init_array .fini_array .jcr .rtemsroset
> >>      02     .data
> >>      03     .vector .bss .work
> >>      04     .xbarrier .robarrier .rwbarrier .stack .nocachenoload
> >>
> >> Then use:
> >>
> >> mkimage -a 0x00400000 -e 0x400145
> >>
> >>
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> >
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