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x32 psABI draft version 0.2

Joseph S. Myers joseph@codesourcery.com
Thu Feb 17 18:14:00 GMT 2011 
On Thu, 17 Feb 2011, Jan Hubicka wrote:

> > REL is horrible pain, we shouldn't ever add new REL targets.
> 
> According to Mozilla folks however REL+RELA scheme used by EABI leads
> to significandly smaller libxul.so size
> 
> According to http://glandium.org/blog/?p=1177 the difference is about 4-5MB
> (out of approximately 20-30MB shared lib)

Well - as noted there, while EABI supports both, binutils just uses REL on 
ARM (except for VxWorks, where it uses RELA).  Supporting both 
simultaneously - linking a mixture of objects with the two types, possibly 
with both mixed within a single object - is much more of a pain (at least 
for the BFD linker, I don't know about gold) than simply supporting one or 
the other for a single ABI - it's required by ARM EABI, but that bit of 
EABI isn't actually supported by binutils.  I think most of the 
target-independent BFD problems with mixing REL and RELA have been ironed 
out by now in the course of Bernd's work on linking objects from TI's C6X 
tools, but it also needs care in the target-specific BFD code (you always 
need to check for each individual relocation what sort it is, rather than 
checking any global flag).

-- 
Joseph S. Myers
joseph@codesourcery.com
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