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Date:      Tue, 23 Nov 2010 17:26:58 +0200
From:      Andriy Gapon <avg@freebsd.org>
To:        John Baldwin <jhb@freebsd.org>
Cc:        Garrett Cooper <yanegomi@gmail.com>, freebsd-hackers@freebsd.org
Subject:   Re: Best way to determine if an IRQ is present
Message-ID:  <4CEBDD42.5010007@freebsd.org>
In-Reply-To: <201011220924.53709.jhb@freebsd.org>
References:  <AANLkTi=%2ByXVrcWDC1QZLA0JWNOQjWG%2Bud_BmwiMXAMXt@mail.gmail.com> <201011220924.53709.jhb@freebsd.org>

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on 22/11/2010 16:24 John Baldwin said the following:
> Well, the real solution is actually larger than described in the PR.  What you 
> really want to do is take the logical CPUs offline when they are "halted".  
> Taking a CPU offline should trigger an EVENTHANDLER that various bits of code 
> could invoke.  In the case of platforms that support binding interrupts to 
> CPUs (x86 and sparc64 at least), they would install an event handler that 
> searches the MD interrupt tables (e.g. the interrupt_sources[] array on x86) 
> and move bound interrupts to other CPUs.  However, I think all the interrupt
> bits will be MD, not MI.

That's a good idea and a comprehensive approach.
One minor technical detail - should an offlined CPU be removed from all_cpus mask/set?

-- 
Andriy Gapon



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