Date: Thu, 7 May 2015 21:25:36 +0800
From: Dave Young <dyoung@redhat.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: "Li, Zhen-Hua" <zhen-hual@hp.com>, dwmw2@infradead.org,
        indou.takao@jp.fujitsu.com, bhe@redhat.com, vgoyal@redhat.com,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org, kexec@lists.infradead.org,
        alex.williamson@redhat.com, ddutile@redhat.com,
        ishii.hironobu@jp.fujitsu.com, bhelgaas@google.com, doug.hatch@hp.com,
        jerry.hoemann@hp.com, tom.vaden@hp.com, li.zhang6@hp.com,
        lisa.mitchell@hp.com, billsumnerlinux@gmail.com, rwright@hp.com
Subject: Re: [PATCH v9 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel
Message-ID: <20150507132536.GA4559@localhost.localdomain>
References: <1426743388-26908-1-git-send-email-zhen-hual@hp.com>
 <20150403084031.GF22579@dhcp-128-53.nay.redhat.com>
 <20150504110551.GD15736@8bytes.org>
 <20150505060931.GB31063@dhcp-128-4.nay.redhat.com>
 <20150505152343.GP15736@8bytes.org>
 <20150506014649.GA14065@dhcp-128-4.nay.redhat.com>
 <20150506081617.GB20611@8bytes.org>
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On 05/06/15 at 10:16am, Joerg Roedel wrote:
> On Wed, May 06, 2015 at 09:46:49AM +0800, Dave Young wrote:
> > For the original problem, the key issue is dmar faults cause kdump kernel
> > hang so that vmcore can not be saved. I do not know the reason why it hangs
> > I think it is acceptable if kdump kernel boot ok with some dma errors..
> 
> It hangs because some devices can't handle the DMAR faults and the kdump
> kernel can't initialize them and will hang itself. For that it doesn't
> matter whether the fault was caused by a read or write request.

Ok, thanks for explanation. so it explains sometimes kdump kernel boot ok
with faults, sometimes it hangs instead.

Dave
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