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Re: [Xen-devel] Re: [patch/rfc] multiprotocol blkback drivers (32-on-64)

To: "Gerd Hoffmann" <kraxel@xxxxxxx>, "Keir Fraser" <keir@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [patch/rfc] multiprotocol blkback drivers (32-on-64)
From: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Date: Wed, 20 Dec 2006 15:47:37 +0000
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Looks a lot nicer now, except that I dislike the replication of the 
structures in now three places. Besides possibly being a maintenance issue, this
now seems worse in terms of scaling up to eventual future protocol versions. I 
understood Keir in a much different way - adding a compiler abstraction header
(which maybe could even make use of Linux' native ones) to include/xen, and
making use of its abstraction directly in xen/include/public/io/blkif.h.


>>> Gerd Hoffmann <kraxel@xxxxxxx> 20.12.06 16:12 >>>

> I think it would be reasonable to put this stuff in a (new) Linux-specific
> header file that wraps the Xen-public blkif.h. We could put just enough
> support in blkif.h itself to allow it to be multiply-compiled. Then
> different OSes can wrap or rewrite blkif.h as they see fit to get the
> required layout for 32-bit and 64-bit ABIs. This conveniently sidesteps some
> of these issues and allows you to concentrate on Linux and GCC, while not
> constraining the implementation choices for anyone else.

Next interation with exactly that implemented, this time even tested
with blkback in all four combinations out of 32/64 dom0, 32/64 guest.


Gerd Hoffmann <kraxel@xxxxxxx>

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