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From: Joerg Roedel <joro@8bytes.org>
To: Takao Indoh <indou.takao@jp.fujitsu.com>
Cc: kexec@lists.infradead.org, iommu@lists.linux-foundation.org,
	dwmw2@infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] intel-iommu: Synchronize gcmd value with global command register
Date: Tue, 2 Apr 2013 16:05:47 +0200	[thread overview]
Message-ID: <20130402140546.GA15687@8bytes.org> (raw)
In-Reply-To: <51591EEE.60401@jp.fujitsu.com>

On Mon, Apr 01, 2013 at 02:45:18PM +0900, Takao Indoh wrote:
> <Current flow on kdump boot>
> enable_IR
>   intel_enable_irq_remapping
>     iommu_disable_irq_remapping  <== IRES/QIES/TES disabled here
>     dmar_disable_qi              <== do nothing
>     dmar_enable_qi               <== QIES enabled
>     intel_setup_irq_remapping    <== IRES enabled

But what we want to do here in the kdumo case is to disable translation
too, right? Because the former kernel might have translation and
irq-remapping enabled and the kdump kernel might be compiled without
support for dma-remapping. So if we don't disable translation here too
the kdump kernel is unable to do DMA.

I agree that disabling translation should be a bit more explicit instead
of the current code.


	Joerg



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  reply	other threads:[~2013-04-02 14:05 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-21  1:32 [PATCH] intel-iommu: Synchronize gcmd value with global command register Takao Indoh
2013-03-26 14:46 ` Joerg Roedel
2013-03-27  5:02   ` Takao Indoh
2013-03-27 10:31     ` Joerg Roedel
2013-04-01  5:45       ` Takao Indoh
2013-04-02 14:05         ` Joerg Roedel [this message]
2013-04-03  7:11           ` Takao Indoh
2013-04-03  8:24             ` David Woodhouse
2013-04-04  5:48               ` Takao Indoh
2013-04-04 14:24                 ` David Woodhouse
2013-04-08  8:57                   ` Takao Indoh
2013-04-05 11:06               ` Joerg Roedel
2013-04-10  4:47                 ` Takao Indoh
2013-04-15  9:00                   ` Takao Indoh
2013-04-15 10:18                     ` Joerg Roedel
2013-04-17  8:48                       ` Takao Indoh

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