linux-kernel - Re: [PATCH 3/3] arm: vfp: Bounce undefined instructions in vectored mode

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Message-ID: <20140918225531.GG5182@n2100.arm.linux.org.uk>
Date:	Thu, 18 Sep 2014 23:55:31 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	linux-arm-kernel@...ts.infradead.org,
	linux-arm-msm@...r.kernel.org, Will Deacon <will.deacon@....com>,
	Stepan Moskovchenko <stepanm@...eaurora.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] arm: vfp: Bounce undefined instructions in
	vectored mode

On Thu, Sep 18, 2014 at 02:43:12PM -0700, Stephen Boyd wrote:
> From: Stepan Moskovchenko <stepanm@...eaurora.org>
> 
> Certain ARM CPU implementations (e.g. Cortex-A15) may not raise a
> floating- point exception whenever deprecated short-vector VFP
> instructions are executed. Instead these instructions are treated
> as UNALLOCATED. Change the VFP exception handling code to emulate
> short-vector instructions even if FPEXC exception bits are not
> set.

Purely out of interest, how much use do these instructions have in
real programs?

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