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: Wed, 27 Mar 2013 11:31:22 +0100 [thread overview]
Message-ID: <20130327103122.GK30540@8bytes.org> (raw)
In-Reply-To: <51527D74.9080209@jp.fujitsu.com>
On Wed, Mar 27, 2013 at 02:02:44PM +0900, Takao Indoh wrote:
> The root cause of this problem is mismatch between iommu->gcmd and
> global command register in the case of kdump. At boot time, initial
> value of iommu->gcmd is zero as I wrote above, but actual global command
> register is *not* zero because some bits like IRE/TE/QIE are already set
> in *first* kernel. Therefore this patch synchronize them to fix this
> problem.
Ok, I understand, but I still don't see why this is a problem. There is
no point for the kdump kernel to preserve hardware state from the
previous kernel. So I think the way it is implemented is correct.
Joerg
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WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Takao Indoh <indou.takao-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
Cc: kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] intel-iommu: Synchronize gcmd value with global command register
Date: Wed, 27 Mar 2013 11:31:22 +0100 [thread overview]
Message-ID: <20130327103122.GK30540@8bytes.org> (raw)
In-Reply-To: <51527D74.9080209-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
On Wed, Mar 27, 2013 at 02:02:44PM +0900, Takao Indoh wrote:
> The root cause of this problem is mismatch between iommu->gcmd and
> global command register in the case of kdump. At boot time, initial
> value of iommu->gcmd is zero as I wrote above, but actual global command
> register is *not* zero because some bits like IRE/TE/QIE are already set
> in *first* kernel. Therefore this patch synchronize them to fix this
> problem.
Ok, I understand, but I still don't see why this is a problem. There is
no point for the kdump kernel to preserve hardware state from the
previous kernel. So I think the way it is implemented is correct.
Joerg
WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Takao Indoh <indou.takao@jp.fujitsu.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
dwmw2@infradead.org, kexec@lists.infradead.org
Subject: Re: [PATCH] intel-iommu: Synchronize gcmd value with global command register
Date: Wed, 27 Mar 2013 11:31:22 +0100 [thread overview]
Message-ID: <20130327103122.GK30540@8bytes.org> (raw)
In-Reply-To: <51527D74.9080209@jp.fujitsu.com>
On Wed, Mar 27, 2013 at 02:02:44PM +0900, Takao Indoh wrote:
> The root cause of this problem is mismatch between iommu->gcmd and
> global command register in the case of kdump. At boot time, initial
> value of iommu->gcmd is zero as I wrote above, but actual global command
> register is *not* zero because some bits like IRE/TE/QIE are already set
> in *first* kernel. Therefore this patch synchronize them to fix this
> problem.
Ok, I understand, but I still don't see why this is a problem. There is
no point for the kdump kernel to preserve hardware state from the
previous kernel. So I think the way it is implemented is correct.
Joerg
next prev parent reply other threads:[~2013-03-27 10:31 UTC|newest]
Thread overview: 46+ 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
2013-03-21 1:32 ` Takao Indoh
2013-03-21 1:32 ` Takao Indoh
2013-03-26 14:46 ` Joerg Roedel
2013-03-26 14:46 ` Joerg Roedel
2013-03-26 14:46 ` Joerg Roedel
2013-03-27 5:02 ` Takao Indoh
2013-03-27 5:02 ` Takao Indoh
2013-03-27 5:02 ` Takao Indoh
2013-03-27 10:31 ` Joerg Roedel [this message]
2013-03-27 10:31 ` Joerg Roedel
2013-03-27 10:31 ` Joerg Roedel
2013-04-01 5:45 ` Takao Indoh
2013-04-01 5:45 ` Takao Indoh
2013-04-01 5:45 ` Takao Indoh
2013-04-02 14:05 ` Joerg Roedel
2013-04-02 14:05 ` Joerg Roedel
2013-04-02 14:05 ` Joerg Roedel
2013-04-03 7:11 ` Takao Indoh
2013-04-03 7:11 ` Takao Indoh
2013-04-03 7:11 ` Takao Indoh
2013-04-03 8:24 ` David Woodhouse
2013-04-03 8:24 ` David Woodhouse
2013-04-04 5:48 ` Takao Indoh
2013-04-04 5:48 ` Takao Indoh
2013-04-04 5:48 ` Takao Indoh
2013-04-04 14:24 ` David Woodhouse
2013-04-04 14:24 ` David Woodhouse
2013-04-04 14:24 ` David Woodhouse
2013-04-08 8:57 ` Takao Indoh
2013-04-08 8:57 ` Takao Indoh
2013-04-05 11:06 ` Joerg Roedel
2013-04-05 11:06 ` Joerg Roedel
2013-04-05 11:06 ` Joerg Roedel
2013-04-10 4:47 ` Takao Indoh
2013-04-10 4:47 ` Takao Indoh
2013-04-10 4:47 ` Takao Indoh
2013-04-15 9:00 ` Takao Indoh
2013-04-15 9:00 ` Takao Indoh
2013-04-15 9:00 ` Takao Indoh
2013-04-15 10:18 ` Joerg Roedel
2013-04-15 10:18 ` Joerg Roedel
2013-04-15 10:18 ` Joerg Roedel
2013-04-17 8:48 ` Takao Indoh
2013-04-17 8:48 ` Takao Indoh
2013-04-17 8:48 ` Takao Indoh
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