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RE: [PATCH 1/2] Add support for O32 FPXX ABI
- From: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- To: Richard Sandiford <rdsandiford at googlemail dot com>
- Cc: "macro at codesourcery dot com" <macro at codesourcery dot com>, "Joseph Myers (joseph at codesourcery dot com)" <joseph at codesourcery dot com>, "binutils at sourceware dot org" <binutils at sourceware dot org>, Rich Fuhler <Rich dot Fuhler at imgtec dot com>
- Date: Thu, 10 Apr 2014 06:50:26 +0000
- Subject: RE: [PATCH 1/2] Add support for O32 FPXX ABI
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B023534DAAAB at LEMAIL01 dot le dot imgtec dot org> <87a9c0xkje dot fsf at talisman dot default> <6D39441BF12EF246A7ABCE6654B023534DC37D at LEMAIL01 dot le dot imgtec dot org> <87ha655s3i dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com> <6D39441BF12EF246A7ABCE6654B023534DC8CF at LEMAIL01 dot le dot imgtec dot org> <871tx9z35k dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com>
Richard Sandiford <firstname.lastname@example.org> writes:
> Matthew Fortune <Matthew.Fortune@imgtec.com> writes:
> > Perhaps call it PT_MIPS_ATTRIBUTES or PT_GNU_ATTRIBUTES if this were
> > done for all architectures.
> Yeah. Might as well make it PT_GNU_ATTRIBUTES, even if it's something
> that targets have to buy into. Probably worth sending a separate RFC to
> the list for that.
I've had some discussion about this with Rich (now on cc). The current
thinking is that we don't want to have the MIPS ABI any more dependent on
the GNU attribute section but instead would prefer to migrate to a MIPS
attribute section. In order to achieve the migration then we would have to
do something like:
1) use the same attribute numbers for the FP abi and MSA abi as used in the
GNU attributes section
2) At link time, if the FP or MSA attribute is set in the gnu attribute
section then copy it to the MIPS attribute section (or if already set
check they match)
3) In the output object only emit the MIPS attribute section (though I
guess it would do no harm to emit both).
4) Perhaps emit both gnu and MIPS attributes in the assembler for
backwards compatibility with older linkers. I think it would be
sufficient to just do this when inferring an attribute from module options.
The explicit .gnu_attribute and .mips_attribute would just set their
Respective attributes but we would be phasing out the explicit use of such
How does that sound? If it is OK would you be happy to review other aspects
of the patch under the assumption that the linker would use this newly
proposed program header scheme on the executables? It will take a few days
to rework this as I have to educate glibc about parsing attribute sections
> > And then somehow get that to be positioned immediately after the notes
> > segment.
> Yeah, at least in the case where it's loadable (and maybe otherwise
> In the bfd linker this would be done by putting the .gnu_attributes in
> the appropriate place in the linker script.
I realised this after sending my email, thanks.