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[Xen-devel] Re: [RFC PATCH 23/35] Increase x86 interrupt vector range

To: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [RFC PATCH 23/35] Increase x86 interrupt vector range
From: Chris Wright <chrisw@xxxxxxxxxxxx>
Date: Mon, 15 May 2006 14:57:20 -0700
Cc: Andrew Morton <akpm@xxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, linux-kernel <linux-kernel@xxxxxxxxxxxxxxx>, Andi Kleen <ak@xxxxxxx>, Chris Wright <chrisw@xxxxxxxxxxxx>, virtualization <virtualization@xxxxxxxxxxxxxx>, Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>
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* Chuck Ebbert (76306.1226@xxxxxxxxxxxxxx) wrote:
> In-Reply-To: <20060509085157.070289000@xxxxxxxxxxxx>
> On Tue, 09 May 2006 00:00:23 -0700, Chris Wright wrote:
> > Remove the limit of 256 interrupt vectors by changing the value
> > stored in orig_{e,r}ax to be the negated interrupt vector.
> > The orig_{e,r}ax needs to be < 0 to allow the signal code to
> > distinguish between return from interrupt and return from syscall.
> > With this change applied, NR_IRQS can be > 256.
> > 
> > Xen extends the IRQ numbering space to include room for dynamically
> > allocated virtual interrupts (in the range 256-511), which requires a
> > more permissive interface to do_IRQ.
> >
> > Signed-off-by: Ian Pratt <ian.pratt@xxxxxxxxxxxxx>
> > Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>
> > Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
> > ---
> AFAIC this could go in anytime.  It's simple, self-contained and makes
> sense even without Xen.

The plan is to split out things like this and push them ahead of the
rest of the batch.

> One minor nit: the IRQ value isn't negated, it's complemented.  The
> comments need to be fixed.

OK, bitwise negated.


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