[PATCH] powerpc: add `cur_cpu_spec` symbol to vmcoreinfo

Michael Ellerman mpe at ellerman.id.au
Fri Sep 15 11:16:08 AEST 2023

Sachin Sant <sachinp at linux.ibm.com> writes:
>> On 14-Sep-2023, at 6:52 PM, Michael Ellerman <mpe at ellerman.id.au> wrote:
>> Sachin Sant <sachinp at linux.ibm.com> writes:
>>>> On 11-Sep-2023, at 2:44 PM, Aditya Gupta <adityag at linux.ibm.com> wrote:
>>>> Presently, while reading a vmcore, makedumpfile uses
>>>> `cur_cpu_spec.mmu_features` to decide whether the crashed system had
>>>> RADIX MMU or not.
>>>> Currently, makedumpfile fails to get the `cur_cpu_spec` symbol (unless
>>>> a vmlinux is passed with the `-x` flag to makedumpfile), and hence
>>>> assigns offsets and shifts (such as pgd_offset_l4) incorrecly considering
>>>> MMU to be hash MMU.
>>>> Add `cur_cpu_spec` symbol and offset of `mmu_features` in the
>>>> `cpu_spec` struct, to VMCOREINFO, so that the symbol address and offset
>>>> is accessible to makedumpfile, without needing the vmlinux file
>>>> Signed-off-by: Aditya Gupta <adityag at linux.ibm.com>
>>>> ---
>>> Thanks for the patch. With this patch applied (along with makedumpfile changes)
>>> I am able to capture vmcore against a kernel which contains commit 8dc9a0ad0c3e
>> I can't find that commit? Was just wondering if it should be referenced
>> in the commit message.
> My bad, I copied that commit id from the email when I first reported this issue
> against linux-next.
> The commit should be 
> 368a0590d954: (powerpc/book3s64/vmemmap: switch radix to use a
> different vmemmap handling function)

OK thanks.

Aditya, can you please rephrase the commit message to mention how that
commit broke the previous behaviour.

Also I don't know what pgd_offset_l4 is?


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