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Date: Thu, 17 Jan 2008 09:25:51 -0700
From: Scott Long <scottl@samsco.org>
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To: Vivek Khera <vivek@khera.org>
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Cc: FreeBSD Stable List <freebsd-stable@freebsd.org>
Subject: Re: What current Dell Systems are supported/work
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Vivek Khera wrote:
> 
> On Jan 15, 2008, at 1:40 PM, John Baldwin wrote:
> 
>>> Where can one go to read up on what MSI is and how it helps us?
>>>
>>> Is enabling it just setting a sysctl?  Does that have to be done in
>>> loader.conf or can it happen later?
>>
>> loader.conf (though it is now default on in RELENG_6).
>>
>> hw.pci.msi_enable=1
>> hw.pci.msix_enable=1
> 
> 
> Thanks for the info.  But can anyone point me to some documentation on 
> why MSI is good for me?
> 

When implemented and used correctly in the hardware and driver, it a
lower overhead interrupt mechanism.  It also expands the number of
interrupt vectors available, making interrupt sharing non-existent (for
right now, at least).

Scott