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From: Jes Sorensen <jes@sgi.com>
To: Matthew Wilcox <matthew@wil.cx>
Cc: akepner@sgi.com, linux-kernel <linux-kernel@vger.kernel.org>,
	rdreier@cisco.com, linux-ia64 <linux-ia64@vger.kernel.org>
Subject: Re: [PATCH 2/3] dma: override "dma_flags_set_dmaflush" for sn-ia64
Date: Wed, 22 Aug 2007 07:44:32 +0000	[thread overview]
Message-ID: <46CBE960.4090702@sgi.com> (raw)
In-Reply-To: <20070821201631.GF9163@parisc-linux.org>

Matthew Wilcox wrote:
> So, let me try to understand ... your hardware allows writes from the
> device to pass other writes from the device?  Doesn't that violate the
> PCI spec?  I'm thinking about this (page 43 of PCI 2.3):

Hi Matthew,

Yes I believe this behavior on sn2 is 'bending' the PCI spec a bit. The
problem is that the NUMA fabric is a routed network in itself so there
can be multiple paths between the device and the physical memory it DMAs
to/from.

Cheers,
Jes

WARNING: multiple messages have this Message-ID (diff)
From: Jes Sorensen <jes@sgi.com>
To: Matthew Wilcox <matthew@wil.cx>
Cc: akepner@sgi.com, linux-kernel <linux-kernel@vger.kernel.org>,
	rdreier@cisco.com, linux-ia64 <linux-ia64@vger.kernel.org>
Subject: Re: [PATCH 2/3] dma: override "dma_flags_set_dmaflush" for sn-ia64
Date: Wed, 22 Aug 2007 09:44:32 +0200	[thread overview]
Message-ID: <46CBE960.4090702@sgi.com> (raw)
In-Reply-To: <20070821201631.GF9163@parisc-linux.org>

Matthew Wilcox wrote:
> So, let me try to understand ... your hardware allows writes from the
> device to pass other writes from the device?  Doesn't that violate the
> PCI spec?  I'm thinking about this (page 43 of PCI 2.3):

Hi Matthew,

Yes I believe this behavior on sn2 is 'bending' the PCI spec a bit. The
problem is that the NUMA fabric is a routed network in itself so there
can be multiple paths between the device and the physical memory it DMAs
to/from.

Cheers,
Jes

  parent reply	other threads:[~2007-08-22  7:44 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-18  0:27 [PATCH 2/3] dma: override "dma_flags_set_dmaflush" for sn-ia64 akepner
2007-08-20  8:24 ` Jes Sorensen
2007-08-20  8:24   ` Jes Sorensen
2007-08-20 16:07   ` akepner
2007-08-20 16:07     ` akepner
2007-08-21 19:35   ` akepner
2007-08-21 19:35     ` akepner
2007-08-21 20:05     ` Randy Dunlap
2007-08-21 20:05       ` Randy Dunlap
2007-08-21 20:55       ` James Bottomley
2007-08-21 20:55         ` James Bottomley
2007-08-22  0:34         ` akepner
2007-08-22  0:34           ` akepner
2007-08-22  1:14           ` James Bottomley
2007-08-22  1:14             ` James Bottomley
2007-08-22  7:39             ` Jes Sorensen
2007-08-22  7:39               ` Jes Sorensen
2007-08-22 14:02               ` James Bottomley
2007-08-22 14:02                 ` James Bottomley
2007-08-22 16:03                 ` Jesse Barnes
2007-08-22 16:03                   ` Jesse Barnes
2007-08-22 16:44                   ` James Bottomley
2007-08-22 16:44                     ` James Bottomley
2007-08-22 16:51                     ` Jesse Barnes
2007-08-22 16:51                       ` Jesse Barnes
2007-08-22 17:04                       ` James Bottomley
2007-08-22 17:04                         ` James Bottomley
2007-08-22 17:03                         ` Jes Sorensen
2007-08-22 17:03                           ` Jes Sorensen
2007-08-22 18:10                           ` James Bottomley
2007-08-22 18:10                             ` James Bottomley
2007-08-23  8:45                             ` Jes Sorensen
2007-08-23  8:45                               ` Jes Sorensen
2007-08-22 17:17                         ` Jesse Barnes
2007-08-22 17:17                           ` Jesse Barnes
2007-08-22 18:13                           ` James Bottomley
2007-08-22 18:13                             ` James Bottomley
2007-08-22 18:44                             ` akepner
2007-08-22 18:44                               ` akepner
2007-08-23  5:58               ` Jeremy Higdon
2007-08-23  5:58                 ` Jeremy Higdon
2007-08-22 15:54             ` akepner
2007-08-22 15:54               ` akepner
2007-08-21 20:16     ` Matthew Wilcox
2007-08-21 20:16       ` Matthew Wilcox
2007-08-21 21:37       ` akepner
2007-08-21 21:37         ` akepner
2007-08-22  7:44       ` Jes Sorensen [this message]
2007-08-22  7:44         ` Jes Sorensen

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