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

Stephen Warren
2013-07-30T16:59:13Z

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?