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Re: -msep-data without -fPIC ?
- From: Gunther Nikl <gni at gecko dot de>
- To: Philippe De Muyter <phdm at macqel dot be>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 17 Jan 2006 12:12:23 +0100
- Subject: Re: -msep-data without -fPIC ?
- References: <200601140121.k0E1LLI17945@mail.macqel.be>
On Sat, Jan 14, 2006 at 02:21:20AM +0100, Philippe De Muyter wrote:
> For an embedded mmu-less m68k target, I would like to generate code
> that will always run at a fixed place in memory, thus not needing to be PIC,
> but that would access a data+bss segment that could be anywhere in memory,
> thus needing accesses to the data segment via %a5 and an offset table.
>
> 1. Does that possibility already exist in gcc (I did not find it) ?
> -msep-data currently does PI-text + PI-data.
AFAICT, this doesn't exist within mainline GCC. The AmigaOS port (which
isn't part of the official sources) implements this scheme, either with
16bit or 32bit displacements. The latter requires a 68020 or better.
Note, you need binutils support as well.
> 2. If it does not exist, I plan to integrate it.
> - From which release or branch should I start ?
> I'd like to work on something that is stable except for my changes.
You have to use current mainlines sources.
> - How is it currently possible in the gcc internals to know if a
> SYMBOL_REF points to the .text or .rodata segments ?
The AmigaOS port uses SYMBOL_REF_FLAG to record this information. I believe
SYMBOL_REF_FLAG is deprecated and there is a newer functionality to achieve
the same.
Gunther