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

[Michael Ellerman]

Hari Bathini <hbathini@xxxxxxxxxxxxx> writes:
> On 28/07/20 7:16 pm, Michael Ellerman wrote:
>> Hari Bathini <hbathini@xxxxxxxxxxxxx> 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.

Ugh, OK.

> 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.

cheers