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Message-ID: <87v9i75dgf.fsf@mpe.ellerman.id.au>
Date: Wed, 29 Jul 2020 11:15:12 +1000
From: Michael Ellerman <mpe@...erman.id.au>
To: Hari Bathini <hbathini@...ux.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Pingfan Liu <piliu@...hat.com>,
Kexec-ml <kexec@...ts.infradead.org>,
Mimi Zohar <zohar@...ux.ibm.com>,
Nayna Jain <nayna@...ux.ibm.com>,
Petr Tesarik <ptesarik@...e.cz>,
Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
Sourabh Jain <sourabhjain@...ux.ibm.com>,
lkml <linux-kernel@...r.kernel.org>,
linuxppc-dev <linuxppc-dev@...abs.org>,
Eric Biederman <ebiederm@...ssion.com>,
Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
Dave Young <dyoung@...hat.com>, Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [RESEND PATCH v5 07/11] ppc64/kexec_file: enable early kernel's OPAL calls
Hari Bathini <hbathini@...ux.ibm.com> writes:
> On 28/07/20 7:16 pm, Michael Ellerman wrote:
>> Hari Bathini <hbathini@...ux.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.
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
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