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Date: Sat, 21 Jul 2012 23:29:17 +1000 (EST)
From: Bruce Evans <brde@optusnet.com.au>
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To: Konstantin Belousov <kib@FreeBSD.org>
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Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org,
	src-committers@FreeBSD.org
Subject: Re: svn commit: r238668 - head/sys/amd64/amd64
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On Sat, 21 Jul 2012, Konstantin Belousov wrote:

> Log:
>  Stop clearing x87 exceptions in the #MF handler on amd64. If user code
>  understands FPU hardware enough to catch SIGFPE and unmask exceptions
>  in control word, then it may as well properly handle return from
>  SIGFPE without causing an infinite loop of #MF exceptions due to
>  faulting instruction restart, when needed.
>
>  Clearing exceptions causes information loss for handlers which do
>  understand FPU hardware, and struct siginfo si_code member cannot be
>  considered adequate replacement for en_sw content due to translation.
>
>  Supposed reason for clearing the exceptions, which is IRQ13 handling
>  oddities, were never applicable to amd64.
>
>  Note: this change will be merged to i386 kernel as well, since we do
>  not support IRQ13 delivery of #MF notifications for some time.
>
>  Requested by:	bde
>  MFC after:	1 week

Thanks.

The comment formatting has lost its constent 2-space sentence breaks.

Bruce