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 for kexec@lists.infradead.org; Fri, 11 Oct 2013 16:47:55 +0000
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Date: Fri, 11 Oct 2013 18:47:19 +0200
From: Richard Weinberger <richard@nod.at>
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Subject: Re: kexec: Clearing registers just before jumping into purgatory
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To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: keir@xen.org, Kees Cook <keescook@chromium.org>, Richard Weinberger <richard.weinberger@gmail.com>, Daniel Kiper <daniel.kiper@oracle.com>, kexec@lists.infradead.org, LKML <linux-kernel@vger.kernel.org>, xen-devel@lists.xen.org, hbabu@us.ibm.com, "Eric W. Biederman" <ebiederm@xmission.com>, jbeulich@suse.com, "H. Peter Anvin" <hpa@linux.intel.com>, Vivek Goyal <vgoyal@redhat.com>, david.vrabel@citrix.com

Am 11.10.2013 18:44, schrieb Matthew Garrett:
> On Fri, Oct 11, 2013 at 06:42:36PM +0200, Richard Weinberger wrote:
>> On Fri, Oct 11, 2013 at 6:39 PM, Matthew Garrett <mjg59@srcf.ucam.org> wrote:
>>> On Fri, Oct 11, 2013 at 06:33:23PM +0200, Richard Weinberger wrote:
>>>> On Fri, Oct 11, 2013 at 5:48 PM, Matthew Garrett <mjg59@srcf.ucam.org> wrote:
>>>>> On Fri, Oct 11, 2013 at 11:44:50AM -0400, Vivek Goyal wrote:
>>>>>
>>>>>> Just Curious. How is it useful. IOW, what's your use case of booting a new
>>>>>> kernel and then jumping back.
>>>>>
>>>>> I'm kexecing into a kernel with a modified /dev/mem, modifying the
>>>>> original kernel and then jumping back into it.
>>>>
>>>> How do you update the original kernel?
>>>
>>> It's still in RAM, so the same way you'd modify any other arbitrary
>>> physical address?
>>
>> So, you have a tool like ksplice which patches the kernel in RAM?
> 
> I have /dev/mem and a list of addresses I want to modify.

But you still need a magic tool which create you this list.
If you have a tool which takes two kernel images and create such
a delta, fine.
I'm interested in that tool. :-)

Thanks,
//richard


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