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Date:   Tue, 7 Apr 2015 17:36:08 +0100 (BST)
From:   "Maciej W. Rozycki" <macro@linux-mips.org>
To:     Ralf Baechle <ralf@linux-mips.org>
cc:     James Cowgill <James.Cowgill@imgtec.com>,
        Markos Chandras <markos.chandras@imgtec.com>,
        linux-mips@linux-mips.org,
        Matthew Fortune <Matthew.Fortune@imgtec.com>,
        Paul Burton <paul.burton@imgtec.com>
Subject: Re: [PATCH] MIPS: asm: elf: Set O32 default FPU flags
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Ralf,

On Thu, 26 Feb 2015, Markos Chandras wrote:

> Set good default FPU flags (FR0) for O32 binaries similar to what the
> kernel does for the N64/N32 ones. This also fixes a regression
> introduced in commit 46490b572544 ("MIPS: kernel: elf: Improve the
> overall ABI and FPU mode checks") when MIPS_O32_FP64_SUPPORT is
> disabled. In that case, the mips_set_personality_fp() did not set the
> FPU mode at all because it assumed that the FPU mode was already set
> properly. That led to O32 userland problems.
> 
> Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
> Cc: Paul Burton <paul.burton@imgtec.com>
> Reported-by: Mans Rullgard <mans@mansr.com>
> Fixes: 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU mode checks")
> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
> ---

 Can you please backport this change to 4.0 ASAP, preferably before it 
hits the actual release?

 It fixes a 3.19->4.0 regression, likely affecting all FPU processors and 
wreaking havoc.  For example I came across a system that boots 3.19 just 
fine, but hangs in `ypbind' with 4.0.  It works again with this change 
applied.

 This is commit 5f067f5c in upstream-sfr.

 Thanks!

  Maciej