From: Joerg Roedel <joro@8bytes.org>
To: "Li, Zhen-Hua" <zhen-hual@hp.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
Date: Tue, 19 Aug 2014 01:23:28 +0200 [thread overview]
Message-ID: <20140818232328.GK9809@8bytes.org> (raw)
In-Reply-To: <1267BB84A242B24E81E0C0C8955CFFC061A4BA26@G9W0343.americas.hpqcorp.net>
On Mon, Aug 18, 2014 at 11:01:56PM +0000, Li, Zhen-Hua wrote:
> There is a bug when Linux running on an HP large system:
> when kdump kernel runs, the hardware is still using the old
> root entry. This causes error message when iommu not finished initialization.
What error message are you seeing? When the kdump kernel boots the iommu
should be still enabled from the old kernel with the old root-entry. So
any in-flight DMA initiated from the old kernel can still pass and there
should be no error messages.
When you clear the root-entry that in-flight DMA might go to another
random location in system memory or just fail, no?
Joerg
next prev parent reply other threads:[~2014-08-18 23:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-18 8:59 [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel Li, Zhen-Hua
2014-08-18 23:01 ` Li, Zhen-Hua
2014-08-18 23:23 ` Joerg Roedel [this message]
2014-08-18 23:27 ` Li, Zhen-Hua
2014-08-19 11:02 ` Joerg Roedel
2014-08-20 9:54 ` Li, ZhenHua
2014-08-18 23:47 ` Li, Zhen-Hua
2014-08-18 23:59 ` Li, Zhen-Hua
2014-08-19 5:49 ` Li, ZhenHua
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