Compiler/TMS320C6657: initialisation data not in cinit

The .const output section is yet another initialized output section, similar to .text.  It can reside in either read-only memory like flash, or read-write memory like RAM.  As such, the .const section does not get initialized by entries in the .cinit section.  

I don't understand why the .const input section from the file EstimateAndApplyGain.obj, a member of the library DPD_release.lib, is not part of the larger output section also named .const.  There must be code in the linker command file which instead makes it part of the output section .DPD_data.  Perhaps this should be changed.

If it is not changed, then view .DPD_data just like .const.  

If the linker command file is not changed, then to avoid this ...

David Pardessus said:

warning: section dsp_program_core1.out(.DPD_data) at 086c780h falls in unconfigured memory (skipped)

The typical method is to modify the ROMS directive in the hex command file.

Please let me know if these suggestions resolve the problem.

Thanks and regards,

-George

Hello George,

I have sent to you the linker command file. We are in rom_model and we copy the content from flash (starting at 0x70400000) to RAM.

If you look at  GROUP (NEAR_DP) > L2SRAM, we have many .const which do not generate error (only .DPD_data fails).

When I look at the code of EstimateAndApplyGain, I find no const declared variable but I have severals local initialized variables. I suspect that (.const:$P$T0$1) contains theses initialization values which must be copied from flash to ram.

Regards,

David

Hello Georges,

1-I don't master all the subtleties of the linker command file ;-)

Can you confirm/deny that cinit only manages initialized but not const data ?

2-"Are you aware this means these .const sections are initialized and allocated directly to L2SRAM?  There is no copy from flash to L2SRAM.  It is your responsibility to get these values copied from the executable .out file to L2SRAM."

I want my const in L2SRAM for performance reason. So, can I write something like that ?

        .DPD_const
        {
            -l=DPD_*.lib(.const)
        } load = FLASH, run = L2SRAM, table(BINIT)

Regards,

David

David Pardessus said:

I don't master all the subtleties of the linker command file ;-)

You are doing just fine.  For more background on this topic, please see the article Linker Command File Primer.

David Pardessus said:

Can you confirm/deny that cinit only manages initialized but not const data ?

Confirmed.

David Pardessus said:

I want my const in L2SRAM for performance reason. So, can I write something like that ?

        .DPD_const
        {
            -l=DPD_*.lib(.const)
        } load = FLASH, run = L2SRAM, table(BINIT)

Yes.  This code creates an output section named .DPD_const.  It is composed of all the .const input sections from all the libraries with a name that begins DPD_ and ends with .lib.  It allocated to FLASH for load, and L2SRAM for run.  There is a copy table entry in the .binit section which is processed by the startup code in the compiler RTS library, which causes .DPD_const to be copied from the load address to the run address.

Thanks and regards,

-George

George,

It becomes clearer, day after day, but the C6x is a big one ;-)

Another question about the boot process on EVM with a XDS probe : I do not use flash like I do on my real target. How works the process of loading the .out generated by the compiler ?

Regards,

David

If you are doing this ...

David Pardessus said:

Another question about the boot process on EVM with a XDS probe

I presume you are controlling execution with Code Composer Studio (CCS).  CCS has access to all the memory in the system.  The loader reads the .out file produced by the compiler.  In the case of initialized sections like .const, it copies them from the .out file to the appropriate memory address.

Thanks and regards,

-George