Re: [PATCH] x86-64: disable the GART before allocate aperture

From: "Yinghai Lu" <yhlu.kernel@gmail.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Alan Cox" <alan@lxorguk.ukuu.org.uk>,
	"Muli Ben-Yehuda" <muli@il.ibm.com>, "Andi Kleen" <ak@suse.de>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Vivek Goyal" <vgoyal@in.ibm.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86-64: disable the GART before allocate aperture
Date: Fri, 22 Jun 2007 14:59:19 -0700	[thread overview]
Message-ID: <86802c440706221459x51630eb3ufd860df393ef05f5@mail.gmail.com> (raw)
In-Reply-To: <m18xabbrp6.fsf@ebiederm.dsl.xmission.com>

On 6/22/07, Eric W. Biederman <ebiederm@xmission.com> wrote:
> Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
>
> For a normal kexec we should shut everything down before the kernel
> transition so it should not be an issue.
>
> YH do you think you can look at simply reserving a portion of the iommu?
> And having the kexec on panic kernel use the reserved portion?
>
two copy region: one for first kernel, and one for second kernel? it
should work.
first kernel is using [64M, 128M), and the second will get assign to
[64M,128M) again.
when it try to memset to clear that region it will cause restart.
in that region, only first 256K can not touched, even read. rest could
be accessed.

YH