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Re: [Xen-devel] xen build error on gcc v4.5.0

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] xen build error on gcc v4.5.0
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Wed, 18 Aug 2010 16:07:30 -0700
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Masroor Vettuparambil <Masroor.Vettuparambil@xxxxxxxx>, M A Young <m.a.young@xxxxxxxxxxxx>
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 On 08/18/2010 12:55 PM, Keir Fraser wrote:
> On 18/08/2010 20:44, "M A Young" <m.a.young@xxxxxxxxxxxx> wrote:
>> On Wed, 18 Aug 2010, Jeremy Fitzhardinge wrote:
>>> Looks like a gcc bug.  Older gccs can compute __RING_SIZE() as a
>>> compile-time constant, but gcc 4.5.0 apparently isn't doing that.  It
>>> is, admittedly, a very complex expression, but gcc shouldn't regress
>>> like this.  I'm not sure how to work around it.
>> One option is to use __CONST_RING_SIZE instead of __RING_SIZE if that is
>> available. I had a similar problem compiling xen with gcc 4.5 where this
>> worked.
> Yes that is exactly why Jan Beulich introduced __CONST_RING_SIZE, in
> xen-unstable:20975. Should be a simple patch to pv_ops netfront/back drivers
> to make use of it.

Ah, OK.  I'll bring it across and sprinkle it around.


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