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Re: The MIPS' statement on R_MIPS_PC16 relocations

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>, Linux-MIPS <linux-mips@linux-mips.org>
Subject: Re: The MIPS' statement on R_MIPS_PC16 relocations
From: Dominic Sweetman <dom@mips.com>
Date: Fri, 28 Feb 2003 09:10:53 +0000
Cc: Mike Uhler <uhler@mips.com>, "Kevin D. Kissell" <kevink@mips.com>, Nigel Stephens <nigel@mips.com>, Dominic Sweetman <dom@mips.com>, Ralf Baechle <ralf@linux-mips.org>
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Maciej W. Rozycki (macro@ds2.pg.gda.pl) writes:

> Thiemo wants to reimplement R_MIPS_PC16 relocations to be useful for
> branches which requires a relocation's addend to be shifted left by two
> before processing and then shifting a calculated value right by two before
> applying to the relocated field (similarly to what is done for R_MIPS_26
> relocations).  The ABI currently defines these relocations to be handled
> without any shifts rendering them useless for branches and probably
> anything else.  I suspect that may actually be a typo or a
> misunderstanding that happened when working on the document. 

The existing definition is nonsense - I won't guess how it happened,
but there's no reason to keep it.  Thiemo has MIPS Technologies'
thanks and blessing in making this change.  Please let our Nigel
Stephens know when it's done (mailto:nigel@mips.com) and he'll
double-check it.

I'm sure you'll put comments in the code noting that this is different
from the document.

There's a more tricky question, which is how we're going to document
this.  I'm currently trying to create a more user-friendly (and
accurate) ABI document, but had not yet got to the relocation types...

-- 
Dominic Sweetman, 
MIPS Technologies (UK)
The Fruit Farm, Ely Road, Chittering, CAMBS CB5 9PH, ENGLAND
phone: +44 1223 706205 / fax: +44 1223 706250 / swbrd: +44 1223 706200
http://www.mips.com


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