Question

I have some data that are zero initialized.

I have allocated an execution region for them in the scatter file.

Some_Execution_Region +0
{
    stuff.o (+RO, +RW, +RI)
}

But I don’t see any segments of zero initialized data in the resulting binary after using fromelf to convert it from the axf file.

The binary file stops right before where the zero initialized data should start.

So the question is how I can make fromelf generate empty region for the zero initialized data in the binary file.

I’ve looked up on the ARM site and have had no luck. I only found out some option to disable zero initialized data. (Doesn’t this mean since I’m not using that option, I should get my zero initialized data in my binary?)

I currently just run fromelf.exe --bin --output=binary.bin elffile.axf, which doesnt generate the zero data.

Answer 1

There’s no need to actually store all of the zeros in the binary. If you are using C then the default is to zero-initialize static variables that are not explicitly initialized to some other value. The C runtime code doesn’t copy zeros from the executable to RAM, it just gets the beginning and ending addresses of the part of RAM that needs to be zeroed. The typical way of telling the linker that variables must be zeroed at startup is to put them in the .bss (blanked static storage) segment, but you shouldn’t need to do this explicitly unless you are writing assembly code.