Re: [PATCH] ARM: kexec: offline non panic CPUs on Kdump panic

Stephen Warren
2013-07-31T17:14:33Z

On 07/31/2013 05:37 AM, Vijay Kilari wrote:
> On Tue, Jul 30, 2013 at 10:29 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 07/30/2013 04:37 AM, Vijay Kilari wrote:
>>> On Fri, Jul 26, 2013 at 10:38 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> ...
>>>> Does a kernel that's used as the crash kernel guarantee:
>>>>
>>>> * Never to re-use the memory that was used by the previous kernel, so
>>>> that the spin loop code/data won't be corrupted, ever, no matter how
>>>> long the crash recovery kernel runs.
>>>>
>>>> * Not use SMP, so there's never a need to re-activate the non-boot CPUs,
>>>> which might not work if they aren't truly disabled but rather just
>>>> running a pin loop?
>>>
>>> From cat /proc/iomem, normal kernel is executed from (0x80xxxxxx) with crash
>>> kernel reserved 64M@0xa0000000
>>>
>>> 80000000-bfffffff : System RAM
>>> 80008000-805aeddf : Kernel code
>>> 805e2000-8063e427 : Kernel data
>>> a0000000-a3ffffff : Crash kernel
>>>
>>> crash kernel is loaded to reserved memory location and is executed from there.
>>> I could confirm this from /proc/iomem when crash kernel is running
>>>
>>> a0000000-a3efffff : System RAM
>>> a0008000-a05aeddf : Kernel code
>>> a05e2000-a063e427 : Kernel data
>>
>> OK, but in the crash dump kernel, is 80008000..8063e427 reserved as
>> well, which would guarantee that the spin loop being executed by the
>> non-crash CPUs won't be corrupted?
>
> The crash dump kernel runs from reserved memory area (0xa0000000 - 0xa3effffff).
> So it should not corrupt the memory area of original kernel that was running
> at 0x80000000,where other CPU's are in spin loop.

What about dynamic allocations?