Re: kexec: Clearing registers just before jumping into purgatory

Richard Weinberger
2013-10-11T16:47:55Z

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