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RE: [RFC 2/2] Update prototype of IFUNC resolver for MIPS
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- Cc: Faraz Shahbazker <Faraz dot Shahbazker at imgtec dot com>, "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>, Robert Suchanek <Robert dot Suchanek at imgtec dot com>
- Date: Mon, 14 Sep 2015 15:56:21 +0000
- Subject: RE: [RFC 2/2] Update prototype of IFUNC resolver for MIPS
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- References: <DCB1C42372B1674B8F912A294CCB775A71684631 at BADAG02 dot ba dot imgtec dot org> <87k2tdn5xt dot fsf at googlemail dot com> <55BFC10F dot 2050503 at imgtec dot com> <87k2tapwq0 dot fsf at googlemail dot com> <55CE5217 dot 5020902 at imgtec dot com> <87io8f2gc9 dot fsf at googlemail dot com> <55D23368 dot 1070705 at imgtec dot com> <87io8dhegb dot fsf at googlemail dot com> <55D269D2 dot 2030208 at imgtec dot com> <87si7h6oyv dot fsf at googlemail dot com> <55D7A3C5 dot 8050600 at imgtec dot com> <87vbc7u1df dot fsf at googlemail dot com> <55E8C3C5 dot 8000107 at imgtec dot com> <alpine dot DEB dot 2 dot 10 dot 1509032210000 dot 24787 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235321270934 at LEMAIL01 dot le dot imgtec dot org>
On Mon, 14 Sep 2015, Matthew Fortune wrote:
> The primary reason for needing FR=1 is for MSA to be usable. Simply
> seeing that MSA is available via a HWCAP is not enough as we have to
> tell the dynamic linker to lock itself into FR=1/FP64 mode while the
> ifunc's module is loaded. In fact it may not even be possible to enter
> FR=1 mode because of the modules which are already loaded.
And it's not possible to have a pseudo-HWCAP bit (with a reservation so
the kernel won't allocate it) that means "can use FP64 mode", or the IFUNC
can't switch to FP64 mode using existing public interfaces so having such
a bit wouldn't be sufficient?
I think the "GNU ifunc - work in progress please ignore" sections of
<https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking>
need expanding to explain the proposed ABI here.
--
Joseph S. Myers
joseph@codesourcery.com