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Hello,
so I stumbled about a use case which is documented in many different parts in the LTS1.3.0 compiler manual, which makes it sometimes hard to gather all the needed information at once.
I wanted to try the topic which is explained here: https://software-dl.ti.com/codegen/docs/tiarmclang/rel1_3_0_LTS/compiler_manual/linker_description/05_linker_command_files/placing-a-section-at-different-load-and-run-addresses-stdz0756565.html#stdz0756565
So in fact placing sections at a different load than run-address. Our use case is to place different code-parts each in external RAM and depending on what the program does load them in the same run-location (of course not both at once, but either the one or the other.).
I followed the example also described here: https://software-dl.ti.com/codegen/docs/tiarmclang/rel1_3_0_LTS/compiler_manual/linker_description/08_using_linker_generated_copy_tables/generating-copy-tables-with-the-table-operator-stdz0750716.html#stdz0750717
so my solution was the following:
in the linker-script:
and inside the source code:
but it won't work.
I can see that the code will be loaded at call copy_in, but somethings wrong.
having opened the memory browser I see the following (I changed the names a bit) before the copy_in (in this case the else-branch):
and after
The copy-tables looks the following:
The copied data is exactly the data which is located in EXTRAM.
what now happens is that the call of the line "new SignalTest()" brings the device to an data abort. The problem is, I can not really debug, because as you see the symbol-demangling uses the first seen symbol and not the actually loaded ones.
It won't crash if linked normaly into the sections, so it's not a problem of the classes/objects.
It doesn't matter if I load the LogTest or SignalTest.
Also I wondered if it may happen because of the sections. So I wondered which sections does the compiler generate? Because just linking the libs I thought it may include all the sections of this library. Which would be fine, but I was not sure about the initialization process of some const-objects which are initialized before call of main(). So I tried playing with the .init_array-section and putting it somewhere else but this did not help.
The documentation has a lack of explanation which sections are generated. There are many chapters which are sometimes redundant but none of those does explain all the possible sections generated, so I can just guess.
I found informations here:
But none are really explaining how to use something. So I tried just putting in the sections text, rodata and data. But if the init_array-section is missing the loaded program won't even run to main but abort inside of __TI_auto_init but I think that may happen because we put the global init_array into TCMA.
So this wasn't a solution anyways.
The problem also happens if we just use one lib with different load- and run-addresses without the UNION statement, so it's not related to overlapping.:
Debugging in code showed that the Constructor-Call does not work correctly. The allocation beforehand with new works, we use our own heap-implementation.
After some steps I saw in the disassembly the program just steps through the copied code, and whats interesting, it does just continue stepping and even steps to the 00000000 parts in exectuion inside this copied part:
after some more steps the abort happens.
So I have no more idea what I am doing wrong here. Any suggestions? Is there a special handling with C++-code?
Best regards
Felix
