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Date:   Sat, 17 Feb 2018 18:47:16 +0100
From:   Fredrik Noring <noring@nocrew.org>
To:     "Maciej W. Rozycki" <macro@mips.com>
Cc:     =?utf-8?Q?J=C3=BCrgen?= Urban <JuergenUrban@gmx.de>,
        linux-mips@linux-mips.org
Subject: Re: [RFC] MIPS: R5900: Workaround for saving and restoring FPU
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Hi Maciej,

>  I thought we agreed the R5900 FPU is unusable for regular Linux software 
> and decided to go for full FPU emulation unconditionally.

Yes, that's true, we are in agreement. I was unaware that the FPU emulation
was complete enough to cover all registers (not only a set of instructions).
Sorry about that. I will simply remove this patch then.

>  We could add a special R5900 mode, denoted with a dedicated 
> Tag_GNU_MIPS_ABI_FP attribute and MIPS ABI Flags FP ABI setting, which 
> would then enable hardware FPU for the selected task, but I suggest we 
> defer any actual code proposals until we have all the design details 
> settled.

Agreed. :)

>  Etc. -- can you reuse MIPS I code here, i.e. use S.D?  GAS should be 
> doing the right thing with `-march=r5900' (if not, then it has a bug).

Possibly, I am somewhat unfamiliar with this area. So let's revisit this FPU
issue after the initial submission.

>  You surely do not want all this MIPS32r2 stuff, or do you?

No, not that I know of.

Fredrik