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From: Tim Deegan <tim@xen.org>
To: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
	Ian Campbell <Ian.Campbell@citrix.com>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>
Subject: Re: [PATCH] libvchan: interdomain communications library
Date: Thu, 25 Aug 2011 11:27:38 +0100	[thread overview]
Message-ID: <20110825102738.GA79827@ocelot.phlegethon.org> (raw)
In-Reply-To: <4E554884.1040109@tycho.nsa.gov>

At 14:52 -0400 on 24 Aug (1314197572), Daniel De Graaf wrote:
> Agreed, barriers are needed for a robust implementation. Since this is
> a shared library and not xen or kernel code, the existing barrier()/wmb()
> functions are not available. The only existing implementations in Xen
> appear to expand to asm("":::"memory") which does not actually implement
> a memory barrier (i.e. MFENCE or similar opcodes).

AIUI on x86_64, writes are guaranteed to be seen in order so the only
thing that barrier has to protect against is the compiler reordering the
writes.

Tim.

-- 
Tim Deegan <tim@xen.org>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

  reply	other threads:[~2011-08-25 10:27 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-19 14:38 [PATCH] libvchan: interdomain communications library Daniel De Graaf
2011-08-22  7:40 ` Vasiliy G Tolstov
2011-08-24 19:28   ` Konrad Rzeszutek Wilk
2011-08-22  9:15 ` Ian Campbell
2011-08-24 18:52   ` Daniel De Graaf
2011-08-25 10:27     ` Tim Deegan [this message]
2011-08-25 18:36       ` Jeremy Fitzhardinge
2011-08-24 18:52   ` [PATCH v2] " Daniel De Graaf
2011-08-26 14:01     ` Ian Jackson
2011-08-29 18:48       ` [PATCH v3] " Daniel De Graaf
2011-08-30 10:32         ` Ian Campbell
2011-08-31 19:17           ` Daniel De Graaf
2011-09-01 16:28             ` Ian Campbell
2011-09-01 16:47               ` Daniel De Graaf
2011-09-01 16:56                 ` Ian Jackson
2011-09-01 17:46                   ` Daniel De Graaf
2011-09-01 16:22 ` [PATCH v4 0/3] " Daniel De Graaf
2011-09-01 16:22   ` [PATCH 1/3] libxc: add xc_gnttab_map_grant_ref_notify Daniel De Graaf
2011-09-01 19:29     ` Konrad Rzeszutek Wilk
2011-09-01 16:22   ` [PATCH 2/3] libxc: add xc_gntshr_* functions Daniel De Graaf
2011-09-01 19:24     ` Konrad Rzeszutek Wilk
2011-09-01 16:22   ` [PATCH 3/3] libvchan: interdomain communications library Daniel De Graaf
2011-09-19 22:43 ` [PATCH v5 0/3] Daniel De Graaf
2011-09-19 22:43   ` [PATCH 1/3] libxc: add xc_gnttab_map_grant_ref_notify Daniel De Graaf
2011-09-21 10:03     ` Ian Campbell
2011-09-21 15:02       ` Daniel De Graaf
2011-09-21 15:25         ` Ian Campbell
2011-09-21 17:07           ` Daniel De Graaf
2011-09-22  8:32             ` Ian Campbell
2011-09-22 18:09               ` Daniel De Graaf
2011-09-19 22:43   ` [PATCH 2/3] libxc: add xc_gntshr_* functions Daniel De Graaf
2011-09-21 10:13     ` Ian Campbell
2011-09-19 22:43   ` [PATCH 3/3] libvchan: interdomain communications library Daniel De Graaf
2011-09-21 10:53     ` Ian Campbell
2011-09-21 16:31       ` Daniel De Graaf
2011-09-22  8:18         ` Ian Campbell
2011-09-21 13:44     ` Ian Campbell
2011-09-22 22:14 ` [PATCH v6 0/3] libxenvchan: " Daniel De Graaf
2011-09-22 22:14   ` [PATCH 1/3] libxc: add xc_gnttab_map_grant_ref_notify Daniel De Graaf
2011-09-30  9:16     ` Ian Campbell
2011-09-30 14:12       ` Ian Jackson
2011-09-30 14:17         ` Ian Campbell
2011-09-22 22:14   ` [PATCH 2/3] libxc: add xc_gntshr_* functions Daniel De Graaf
2011-09-22 22:14   ` [PATCH 3/3] libvchan: interdomain communications library Daniel De Graaf
2011-09-30  7:51   ` [PATCH v6 0/3] libxenvchan: " Vasiliy Tolstov
2011-09-30  8:28     ` Vasiliy Tolstov
2011-09-30 14:40       ` Daniel De Graaf
2011-11-24 20:02         ` Anil Madhavapeddy
2011-11-25 16:53           ` Daniel De Graaf
2011-11-25 16:54             ` [PATCH] libxc: Fix checks on grant notify arguments Daniel De Graaf
2011-12-01 18:20               ` Ian Jackson
2011-11-25 16:56             ` [PATCH 1/2] xen/events: prevent calling evtchn_get on invlaid channels Daniel De Graaf
2011-11-25 16:56               ` [PATCH 2/2] xen/gntalloc: release grant references on page free Daniel De Graaf
2011-11-25 18:37                 ` [PATCH] xen/gntalloc: fix reference counts on multi-page mappings Daniel De Graaf
2011-09-30  8:34   ` [PATCH v6 0/3] libxenvchan: interdomain communications library Ian Campbell
2011-09-30  8:37     ` [PATCH] libxc: osdep: report missing backends in common code Ian Campbell
2011-10-06 18:44     ` [PATCH v6 0/3] libxenvchan: interdomain communications library Ian Jackson
2011-10-07  8:41       ` Roger Pau Monné
2011-10-07  9:15         ` Keir Fraser
2011-10-07  9:48           ` Ian Jackson
2011-10-07 10:22             ` Roger Pau Monné

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