Re: [gccsdk] malloc

> Sorry, I think we might have our wires crossed :-) It's the address
> returned by malloc that needs to be 8 byte aligned rather than the
> number of bytes returned.
Yes I understand this.. But isn't malloc (unix) using padding ?

> The problem is, some instructions, for example LDRD, require an 8
> byte aligned base address. If we use malloc to allocate a structure
> that starts with an 8 byte type that the compiler might use LDRD to
> load and malloc returns a 4 byte (but not 8) aligned address, then it
> will probably abort.

I have been testing with mallocs , and the addresses returned seems to
be 8 byte aligned. I guess gcc has the answer.

> In fact, I fell foul of something similar in the dynamic linker
> when porting GCC 8/10; I had to ensure that the library data segments
> retained the original alignment that the compiler/linker gave them to
> prevent LDRD from aborting.
> I suspect that newer versions (than 4.7) of GCC will expect malloc'ed
> memory to be 8 byte aligned and pad structures accordingly.
> Unfortunately, we're a bit behind there, and I think it is something we
> need to look at.
OK

The reason for all this is , malloc fails for me , so I decided to roll my own.
In that I wanted to make sure that the mem and addresses are the same as
expected from malloc.

Michael

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