linux-kernel - Re: [PATCH v8 02/10] iommu/vt-d: Items required for kdump

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Date:	Mon, 12 Jan 2015 17:06:46 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	"Li, Zhen-Hua" <zhen-hual@...com>, dwmw2@...radead.org,
	indou.takao@...fujitsu.com, bhe@...hat.com, dyoung@...hat.com,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, kexec@...ts.infradead.org,
	alex.williamson@...hat.com, ddutile@...hat.com,
	ishii.hironobu@...fujitsu.com, bhelgaas@...gle.com,
	doug.hatch@...com, jerry.hoemann@...com, tom.vaden@...com,
	li.zhang6@...com, lisa.mitchell@...com, billsumnerlinux@...il.com,
	rwright@...com
Subject: Re: [PATCH v8 02/10] iommu/vt-d: Items required for kdump

On Mon, Jan 12, 2015 at 10:29:19AM -0500, Vivek Goyal wrote:
> Kdump has the notion of backup region. Where certain parts of old kernels
> memory can be moved to a different location (first 640K on x86 as of now)
> and new kernel can make use of this memory now.
> 
> So we will have to just make sure that no parts of this old page table
> fall into backup region.

Uuh, looks like the 'iommu-with-kdump-issue' isn't complicated enough
yet ;)
Sadly, your above statement is true for all hardware-accessible data
structures in IOMMU code. I think about how we can solve this, is there
an easy way to allocate memory that is not in any backup region?

Thanks,

	Joerg

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