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RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- Cc: "'libc-alpha at sourceware dot org'" <libc-alpha at sourceware dot org>, "Moore, Catherine (Catherine_Moore at mentor dot com)" <Catherine_Moore at mentor dot com>, 'Andrew Pinski' <pinskia at gmail dot com>, "Rich Felker (dalias at libc dot org)" <dalias at libc dot org>, Rich Fuhler <Rich dot Fuhler at imgtec dot com>, "'macro at codesourcery dot com'" <macro at codesourcery dot com>
- Date: Fri, 31 Oct 2014 13:52:16 +0000
- Subject: RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B0235320F1A039 at LEMAIL01 dot le dot imgtec dot org> <Pine dot LNX dot 4 dot 64 dot 1410022033580 dot 21905 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235320F1EEE5 at LEMAIL01 dot le dot imgtec dot org> <Pine dot LNX dot 4 dot 64 dot 1410072108360 dot 17516 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235320F2BEE7 at LEMAIL01 dot le dot imgtec dot org> <Pine dot LNX dot 4 dot 64 dot 1410172051110 dot 14369 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235320F2C6F3 at LEMAIL01 dot le dot imgtec dot org> <Pine dot LNX dot 4 dot 64 dot 1410191538160 dot 15206 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235320F2D050 at LEMAIL01 dot le dot imgtec dot org> <Pine dot LNX dot 4 dot 64 dot 1410302359300 dot 16421 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235320F5D202 at LEMAIL01 dot le dot imgtec dot org>
On Fri, 31 Oct 2014, Matthew Fortune wrote:
> > So you might assume that use of new instructions means a kernel with
> > support for them (and thus a kernel that sets the relevant HWCAP bit), but
> > not a glibc with support for them (so addition of checks in future for
> > HWCAP bits for new ASEs adds safety, but from a starting point where old
> > glibc will run binaries with the new instructions, just without the safety
> > check that the ASE is in fact supported).
>
> I'm happy to work on that basis if you are OK in principle at least with
> adding safety checks as and when we have HWCAPs defined for protection.
OK in principle (though I believe we'll want a way to disable those checks
at compile / link time of a binary that uses ASEs with runtime
conditionals).
> So the plan is:
>
> * Remove any ASE related checks from this patch
> * Allow ASE checks to be added when there are HWCAPs defined
> * Leave the flags2 check as a way of avoiding bumping the ABIVERSION
> for future ABI changes. (Not that I'm in any rush to try modifying
> the MIPS ABIs again!)
* Update the ABI document to state how unknown bits in flags1 and flags2
should be handled (ignored, and cause the binary to be rejected,
respectively).
> * If a future ASE needs some special handling which can't be dealt with
> via flags2 then that would need an ABIVERSION bump.
>
> Do you think that covers it?
* libc-abis should follow the direction in
<https://sourceware.org/ml/libc-alpha/2014-10/msg00578.html> (meaning you
add to the MIPS file, rather than being relative to a tree with a patch
merging the files applied).
* As <https://sourceware.org/ml/libc-alpha/2014-10/msg00352.html> was
approved it should be committed so the patch doesn't need to be relative
to a tree with another uncommitted patch applied either.
--
Joseph S. Myers
joseph@codesourcery.com
- References:
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information
- RE: [PATCHv3, MIPS] Add support for O32 FPXX and program header based ABI information