Subject: Re: [PATCH 6/29] x86-apic-virtwire-on-shutdown
From: Len Brown <len.brown@intel.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@osdl.org>, fastboot@lists.osdl.org,
       linux-kernel@vger.kernel.org
In-Reply-To: <x86-apic-virtwire-on-shutdown-11061198973730@ebiederm.dsl.xmission.com>
References: <x86-apic-virtwire-on-shutdown-11061198973730@ebiederm.dsl.xmission.com>
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Date: 24 Jan 2005 22:54:19 -0500
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On Wed, 2005-01-19 at 02:31, Eric W. Biederman wrote:
> When coming out of apic mode attempt to set the appropriate
> apic back into virtual wire mode.  This improves on previous versions
> of this patch by by never setting bot the local apic and the ioapic
> into veritual wire mode.
> 
> This code looks at data from the mptable to see if an ioapic has
> an ExtInt input to make this decision.  A future improvement
> is to figure out which apic or ioapic was in virtual wire mode
> at boot time and to remember it.  That is potentially a more accurate
> method, of selecting which apic to place in virutal wire mode.
> 

The call to find_isa_irq_pin() will always fail on ACPI-enabled systems,
so this patch is a NO-OP unless the system is booted in MPS mode.

Do we really want to be adding this complexity for obsolete systems? 
Are there systems that fail without this patch?

-Len


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