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From: Muli Ben-Yehuda <muli@il.ibm.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Chandru <chandru@in.ibm.com>,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	jdmason@kudzu.us
Subject: Re: [RFC] [Patch] calgary iommu: Use the first kernel's tce tables in kdump
Date: Thu, 13 Mar 2008 17:49:19 +0200	[thread overview]
Message-ID: <20080313154919.GE7114@il.ibm.com> (raw)
In-Reply-To: <20080312180806.GB13549@redhat.com>

On Wed, Mar 12, 2008 at 02:08:06PM -0400, Vivek Goyal wrote:

> Agree. Ignoring all the DMA errors in kdump kernel does not sound
> very good.
> 
> On a side note, typically how much time does it take to for DMA
> operations to finish. Can we wait for a random amount of time in
> second kernel, hoping all the DMA operations are complete, and then
> setup a new table?
> 
> This can be atleast a stop gap solution till we come up with a good
> solution?

The problem as I understand it is that when we boot into the kdump
kernel we have left-over devices from the old kernel which are active
and initiating DMA's. This is fine as long as Calgayr is also active
(with the old kernel's mappings). Once we initialize Calgary (in the
kdump) kernel with the new mappings, however, it starts trapping all
those DMA's. We can't wait for them to stop, because that will only
happen when the device is re-initialized (or otherwise quiesced).

Cheers,
Muli

  reply	other threads:[~2008-03-14 16:50 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-09 20:40 chandru
2007-10-09 21:06 ` Muli Ben-Yehuda
2007-10-10  5:30   ` Vivek Goyal
2007-10-14  5:41     ` Muli Ben-Yehuda
2007-10-15  6:29       ` Vivek Goyal
2007-12-24  5:15         ` Chandru
2008-03-10 13:20           ` Chandru
2008-03-10 16:09             ` Andrew Morton
2008-06-21 12:11               ` Chandru
2008-06-21 12:25                 ` Mark Salyzyn
2008-06-23 19:29                 ` Muli Ben-Yehuda
2008-07-15  8:45                   ` Chandru
2008-07-15 10:52                     ` Muli Ben-Yehuda
2008-07-17 23:14                     ` Andrew Morton
2008-07-20  9:42                       ` Muli Ben-Yehuda
2008-03-11 13:29             ` Vivek Goyal
2008-03-12  5:08               ` Chandru
2008-03-12  9:58                 ` Muli Ben-Yehuda
2008-03-12 18:08                   ` Vivek Goyal
2008-03-13 15:49                     ` Muli Ben-Yehuda [this message]
2007-10-10  5:37 ` Vivek Goyal

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