Re: [RESEND PATCH v5 07/11] ppc64/kexec_file: enable early kernel's OPAL calls

Hari Bathini
2020-07-28T19:25:05Z

On 28/07/20 7:16 pm, Michael Ellerman wrote:
> Hari Bathini <hbathini@linux.ibm.com> writes:
>> Kernel built with CONFIG_PPC_EARLY_DEBUG_OPAL enabled expects r8 & r9
>> to be filled with OPAL base & entry addresses respectively. Setting
>> these registers allows the kernel to perform OPAL calls before the
>> device tree is parsed.
>
> I'm not convinced we want to do this.
>
> If we do it becomes part of the kexec ABI and we have to honour it into
> the future.
>
> And in practice there are no non-development kernels built with OPAL early
> debugging enabled, so it's not clear it actually helps anyone other than
> developers.
>

Hmmm.. kexec-tools does it since commit d58ad564852c ("kexec/ppc64
Enable early kernel's OPAL calls") for kexec_load syscall. So, we would
be breaking kexec ABI either way, I guess.

Let me put this patch at the end of the series in the respin to let you
decide whether to have it or not..

Thanks
Hari