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Re: [Xen-devel] Re: [patch 21/26] Xen-paravirt_ops: Use the hvc console

To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [patch 21/26] Xen-paravirt_ops: Use the hvc console infrastructure for Xen console
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Fri, 16 Mar 2007 11:58:19 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Andi Kleen <ak@xxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>, Wright <chrisw@xxxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxx, Ingo Molnar <mingo@xxxxxxx>, Chris@xxxxxxxxxxxxx
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On 16/3/07 11:41, "Andrew Morton" <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

>> It's needed for writing data /after/ reading the consumer index that shows
>> you have space to write. Looking through xenbus_comms.c I think all the
>> barriers are correct except there is a spurious extra mb() in xb_read(),
>> where there is a later rmb() which is sufficient by itself. All the others
>> have a purpose.
> If Ingo couldn't work this out from reading the code then nobody else can,
> and we have a maintainability problem which can only be solved with
> adequate commenting.

Agreed. I've fixed up the commenting, removed the spurious mb(), and I just
need Jeremy to merge that change into the Xen pv_ops patchset. :-)

 -- Keir

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