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Date: Tue, 16 Sep 2008 10:24:48 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Dean Nelson <dcn@sgi.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Alan Mayer <ajm@sgi.com>,
       jeremy@goop.org, rusty@rustcorp.com.au, suresh.b.siddha@intel.com,
       torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
       "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
       Yinghai Lu <Yinghai.lu@amd.com>
Subject: Re: [RFC 0/4] dynamically allocate arch specific system vectors
Message-ID: <20080916082448.GA17287@elte.hu>
References: <489C6844.9050902@sgi.com> <20080811165930.GI4524@elte.hu> <48A0737F.9010207@sgi.com> <m1y733mjdh.fsf@frodo.ebiederm.org> <20080911152304.GA13655@sgi.com> <20080914153522.GJ29290@elte.hu> <20080915215053.GA11657@sgi.com>
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* Dean Nelson <dcn@sgi.com> wrote:

> > while i understand the UV_BAU_MESSAGE case (TLB flushes are 
> > special), why does sgi-gru and sgi-xp need to go that deep? They are 
> > drivers, they should be able to make use of an ordinary irq just 
> > like the other 2000 drivers we have do.
> 
> The sgi-gru driver needs to be able to allocate a single irq/vector 
> pair for all CPUs even those that are not currently online. The sgi-xp 
> driver has similar but not as stringent needs.

why does it need to allocate a single irq/vector pair? Why is a regular 
interrupt not good?

	Ingo