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Re: [RFA] ARM OABI - pc-relative relocations
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Jerome Guitton <guitton at ACT-Europe dot FR>
- Cc: Richard dot Earnshaw at arm dot com, binutils at sources dot redhat dot com
- Date: Mon, 15 Dec 2003 14:11:23 +0000
- Subject: Re: [RFA] ARM OABI - pc-relative relocations
- Organization: ARM Ltd.
- Reply-to: Richard dot Earnshaw at arm dot com
> Richard Earnshaw (rearnsha@arm.com):
>
> > BTW I think you must have an out of date document.... In ARM ELF (SWS ESPC
> > 0003 B-02), which was the final draft, the text is now in section 4.5
>
> OK, thank you. I consulted it from
> http://www.arm.com/documentation/Software_Development_Tools/index.html.
> The version provided on the page is not up to date anymore.
>
> > In the "ABI for the ARM Architecture" (http://www.arm.com/products/DevTools
> > /ABI.html), we've gone back to the current ELF specs and taken a much more
> > traditional approach, so now the REL and RELA addends follow the current
> > rules. This introduces a further benefit for RELA type relocations:
> > idempotency -- you can reapply the relocation and you should get the same
> > result. This allows, for example, images to be re-positioned after
> > linking if they preserve their relocations in RELA form.
>
> Ouch! That is perfectly reasonable, but I have a problem. I am
> targetting VxWorks 5.5 on ARM. WRS' tools uses RELA, with the old ABI
> definition... And I am interested in making a the GNU tools and WRS
> tools compatible.
>
> Would it make sense to add a new target in the binutils to support
> this configuration?
Yes, almost certainly that's what we will have to do. It's not just
binutils but the compiler ABI also changes (data alignments etc), so it
really does need a completely new config triplet.
R.