making a flash image [was: m68k/efi332 pb in boot_card() in flash]

Jean-Baptiste Maillet busy.lab at
Fri May 23 17:54:42 UTC 2003


Thanks to Aaron and Matt for their suggestions.
I think there's something fundamental I did not understood in the 
process of making a flash image.

(summary: I use a modified efi332 bsp (68332). The modifications are limited to chip
select + linker script. It runs fine in ram. When in flash, it looks like I don't go beyond the line:
bsp_isr_level = rtems_initialize_executive_early( &BSP_Configuration, &Cpu_table ); boot_card().
I did some trials with the mrm332 bsp instead of efi332 (sources from last snapshot), close enough from efi332 and got exactly the same result.)

In order to prepare a flash image:

1 - in /opt/rtems/CPU/BSP/lib, I backup the linkcmds and copy the linkcmds_ROM to linkcmds or pass an option to ld in the Makefile

2 - I rebuild my app

Then the image has code in rom but data (which code address refers to) and bss are in ram, as can be seen by a rtems-CPU-objdump -h
3 - I issue an CPU-rtems-objcopy --adjust-section-vma .data=XXXX myapp.nxe myapp.flash
With XXXX being the size of the text. As I understood from the BSP & device driver manual, section 4-5. This does not work because (I think) there's an offset before the text for reset and vbr vector + EVT. I can see that BSP_Configuration is wrong (all ffffffff).

4 - I then use a CPU-rtems-objcopy --adjust-section-vma .data=YYYY myapp.nxe myapp.flash
With YYYY being size of text+offset. Better now: BSP_Configuration or Cpu_Table are OK for instance.

5 - Then I think that it's cumbersome to calculate this size+offset thing for each app, script or not, and decide to be smarter than I'm for real. In the linker script, I declare a .data_rom section wich goes in rom, with the same content that the .data section. I of course change the symbols (_data_start_rom instead of _data_start etc). I let the regular .data section so that the code refer to. I declare the new symbols as extern in the code and instead of copying from _etext, I copy from _data_start_rom. Of course it will be a problem for ram linking (symbol undefined), but my pb is flash right now. It still works the same, BSP_Configuration is OK etc. But still crash.

6 - then I see that after data copying, the efi332 BSP copy the EVT in the beginning of ram, silently overwriting the beginning of my data. I don't see an easy way of controlling that and...

7 - ... gave a try with a quick port from the mrm332 BSP just for a try, and followed the same steps 3-4-5. The EVT goes after the data in ram if I saw correctly, so that should be better, but nope.

Same symptoms from 2 different BSP: there must be something I missed completly in the process of going from an app build using a linkcms_ROM script to an actual flash image. ld scripts, use of objdump and objcopy, all together?

I would be glad if someone please explained me how terribly wrong I am.
Jean-Baptiste Maillet

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