Message-ID: <4920BF62.10700@zytor.com>
Date: Sun, 16 Nov 2008 16:48:34 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Yinghai Lu <yinghai@kernel.org>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Andrew Morton <akpm@linux-foundation.org>, mingo@elte.hu,
       tglx@linutronix.de, linux-kernel@vger.kernel.org, travis@sgi.com
Subject: Re: [PATCH] sparse_irq aka dyn_irq v13
References: <491434FB.2050904@kernel.org> <20081107124957.GA21709@elte.hu>	 <49168BD3.5010204@kernel.org> <20081109073813.GA17180@elte.hu>	 <86802c440811090003g5ac53822y852a4c1096228f8b@mail.gmail.com>	 <20081110094033.GL22392@elte.hu>	 <20081110015511.453a801e.akpm@linux-foundation.org>	 <4918065A.6050402@kernel.org> <20081110100329.GA19970@elte.hu>	 <491A9F87.8040403@kernel.org> <20081112120814.GG11352@elte.hu>	 <491C8B38.9060901@kernel.org>	 <20081113131850.d94fb229.akpm@linux-foundation.org> <1226869137.7178.175.camel@pasglop> <4920B069.5020203@kernel.org> <4920B15E.6090200@zytor.com> <4920B2A4.4040900@kernel.org> <4920B3E3.4050707@zytor.com> <4920B911.7060504@kernel.org> <4920BA3A.5090100@zytor.com> <4920BCA8.6080600@kernel.org>
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Yinghai Lu wrote:
> H. Peter Anvin wrote:
>> It would, however, be a good idea if IOAPICs had their numbers assigned
>> at detection time, as opposed to when the interrupt is registered, thus
>> making it a stable number for a single boot, at least.  The same is
>> probably true for MSI(-X); we could assign it a range of numbers when
>> the device is enumerated (as opposed to when a driver is activated), but
>> I don't know to what extent that is likely to cause more troubles than
>> it solves.
> 
> how to find the range for MSIX, one device/func may need a lot. for example, niu driver could use 20 MSI-X for one port. (one dev/func)
> some could use 256. we only know that when driver is loaded.
> So as Eric said, just try to use 12bits (4k range) for them.
> 

You can know how many vectors are exported in generic code.  However,
using 4k per should be fine.

	-hpa
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