Date: Sat, 21 Jul 2012 23:29:17 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Konstantin Belousov <kib@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r238668 - head/sys/amd64/amd64 Message-ID: <20120721232459.J2515@besplex.bde.org> In-Reply-To: <201207211305.q6LD5YiC035936@svn.freebsd.org> References: <201207211305.q6LD5YiC035936@svn.freebsd.org>
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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
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