From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [Xen-devel] [PATCH 0001/001] xen: multi page ring support for
	block devices
Date: Thu, 15 Mar 2012 08:51:34 +0000
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To: Jan Beulich <JBeulich@suse.com>
Cc: "jeremy@goop.org" <jeremy@goop.org>, "konrad.wilk@oracle.com" <konrad.wilk@oracle.com>, "waldi@debian.org" <waldi@debian.org>, "joe.jin@oracle.com" <joe.jin@oracle.com>, "weiyi.huang@gmail.com" <weiyi.huang@gmail.com>, "virtualization@lists.linux-foundation.org" <virtualization@lists.linux-foundation.org>, Justin Gibbs <justing@spectralogic.com>, Paul Durrant <Paul.Durrant@citrix.com>, David Vrabel <david.vrabel@citrix.com>, Santosh Jodh <Santosh.Jodh@citrix.com>, "<konrad@darnok.org>" <konrad@darnok.org>, "dgdegra@tycho.nsa.gov" <dgdegra@tycho.nsa.gov>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, "lersek@redhat.com" <lersek@redhat.com>
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On Thu, 2012-03-15 at 08:03 +0000, Jan Beulich wrote:
> >>> On 14.03.12 at 18:01, Justin Gibbs <justing@spectralogic.com> wrote:
> > While we're talking about fixing ring data structures, can RING_IDX
> > be defined as a "uint32_t" instead of "unsigned int".  The structure
> > padding in the ring macros assumes RING_IDX is exactly 4 bytes,
> > so this should be made explicit.  ILP64 machines may still be a way
> > out, but the use of non-fixed sized types in places where size really
> > matters just isn't clean.
> 
> Yes, if we're going to rev the interface, then any such flaws should be
> corrected.

There has been talk of doing something similar for netif too. IIRC the
netchannel2 work included a new generic ring scheme with support for
variable sized req/rsp elements and such.

If we are going to rev the rings then should we try and use a common
ring mechanism? I think so. If so then we could do worse than to start
from the netchannel2 ring stuff and/or concepts?

Looks like that is
http://xenbits.xen.org/ext/netchannel2/linux-2.6.18/log/075f6677a290/include/xen/interface/io/uring.h
still a bit nc2 specific though.

Ian.