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Re: [PATCH] MIPS EVA ASE Support
- From: "Maciej W. Rozycki" <macro at codesourcery dot com>
- To: David Daney <ddaney dot cavm at gmail dot com>
- Cc: "Pinski, Andrew" <Andrew dot Pinski at caviumnetworks dot com>, Richard Sandiford <rdsandiford at googlemail dot com>, "Moore, Catherine" <Catherine_Moore at mentor dot com>, "binutils at sourceware dot org" <binutils at sourceware dot org>
- Date: Tue, 11 Jun 2013 01:10:10 +0100
- Subject: Re: [PATCH] MIPS EVA ASE Support
- References: <FD3DCEAC5B03E9408544A1E416F11242F8FC6EE7 at NA-MBX-01 dot mgc dot mentorg dot com> <87fvwz9hsg dot fsf at talisman dot default> <FD3DCEAC5B03E9408544A1E416F11242F8FC9639 at NA-MBX-01 dot mgc dot mentorg dot com> <87bo7g99yn dot fsf at talisman dot default> <FD3DCEAC5B03E9408544A1E416F11242F8FC9A3B at NA-MBX-01 dot mgc dot mentorg dot com> <87ip1l7oz9 dot fsf at talisman dot default> <alpine dot DEB dot 1 dot 10 dot 1306102316550 dot 16287 at tp dot orcam dot me dot uk> <51B65EA9 dot 7000300 at gmail dot com>
On Tue, 11 Jun 2013, David Daney wrote:
> > So overall I think we want to have another knob, perhaps just -mtlbinv
> > (name to be agreed upon), to control these instructions in addition to
> > -meva rather than to enable them for from what would have to be
> > -mips32r3/-mips64r3 (yes, we're at rev. 3 already in case someone missed
> > it ;) ). I don't think we've had a precedent where optional instructions
> > are enabled unconditionally for a sufficiently high ISA level to possibly
> > support them.
>
> Rev. 5 is the most recent as far as I can tell (rev. 4 was skipped).
Well, I have seen rev. 5 mentioned recently, but I have yet to see actual
architecture documentation. So for FSF projects such as binutils that
rely on (require) public documentation rev. 3 is the most recent.
> I guess -mtlbinv would also be implied as part of the various -mcpu=xxxx
> options. I think you also need to be able to control it via ".set tlbinv" in
> the source code too.
Yes, of course, all the usual infrastructure implied.
> It would be nice to give floating point instructions the same treatment..
I'm not sure what you mean -- paired-single support? I think this is the
only optional part of the FPU instruction set that we have not subsetted
correctly -- the MIPS V ISA has never been implemented by itself and its
added instruction set became optional with the MIPS64r1/MIPS32r2 ISA.
Then we've got the MIPS-3D ASE instructions correctly covered and the
remaining FPU instructions are tied to the respective ISAs they have been
introduced with. Have I missed anything?
Maciej