Date: Thu, 13 Dec 2012 13:00:27 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r243764 - head/sys/x86/x86 Message-ID: <50C9B54B.1080302@FreeBSD.org> In-Reply-To: <201212061540.42393.jhb@freebsd.org> References: <201212011816.qB1IGE2Y064317@svn.freebsd.org> <201212061540.42393.jhb@freebsd.org>
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on 06/12/2012 22:40 John Baldwin said the following: > On Saturday, December 01, 2012 1:16:14 pm Andriy Gapon wrote: >> Author: avg >> Date: Sat Dec 1 18:16:14 2012 >> New Revision: 243764 >> URL: http://svnweb.freebsd.org/changeset/base/243764 >> >> Log: >> ioapic_program_intpin: program high bits before low bits >> >> Programming the low bits has a side-effect if unmasking the pin if it is >> not disabled. So if an interrupt was pending then it would be delivered >> with the correct new vector but to the incorrect old LAPIC. >> >> This fix could be made clearer by preserving the mask bit while >> programming the low bits and then explicitly resetting the mask bit >> after all the programming is done. >> >> Probability to trip over the fixed bug could be increased by bootverbose >> because printing of the interrupt information in ioapic_assign_cpu >> lengthened the time window during which an interrupt could arrive while >> a pin is masked. > > Can you expand the comment to say that you write 'low' second since it may > clear the masked bit? > Will do. -- Andriy Gapon
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