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Re: [Xen-devel] [PATCH] ioemu: unmap INTx interrupt on hot-remove

To: Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] ioemu: unmap INTx interrupt on hot-remove
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Fri, 27 Mar 2009 08:26:28 +1100
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On Thu, Mar 26, 2009 at 05:11:29PM +0900, Yuji Shimada wrote:
> On Thu, 26 Mar 2009 16:12:38 +1100
> Simon Horman <horms@xxxxxxxxxxxx> wrote:
> 
> > > +char mapped_machine_irq[PT_NR_IRQS] = {0};
> > 
> > This only initialises the first element of mapped_machine_irq[] to 0.
> 
> Do you have any issue relating to this code?
> I think remaining elements are initialized to 0.

My issue is that the code doesn't seem to be correct - though I have not
experienced any problems.

My understanding is that it may well be the case that the rest of the array
is initialised to zero, by virtue of being a page that hasn't been used
since being received from the kernel. But I don't believe that there are
any guarantees that it doesn't contain non-zero values.

If my assumptions are wrong and it is the case that the contents of the
array is guaranteed to be zeroed then the "{0}" seems to be misleading and
it could just be removed.

-- 
Simon Horman
  VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
  H: www.vergenet.net/~horms/             W: www.valinux.co.jp/en


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