linux-kernel - Re: [PATCHv8 17/17] ACPI: tables: Print MULTIPROC

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Message-ID: <2f8c2032-d8ac-4be2-a409-9880c310aead@intel.com>
Date: Thu, 29 Feb 2024 10:19:11 +1300
From: "Huang, Kai" <kai.huang@...el.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>, Peter Zijlstra
	<peterz@...radead.org>, Adrian Hunter <adrian.hunter@...el.com>, "Kuppuswamy
 Sathyanarayanan" <sathyanarayanan.kuppuswamy@...ux.intel.com>, "Elena
 Reshetova" <elena.reshetova@...el.com>, Jun Nakajima
	<jun.nakajima@...el.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, Tom
 Lendacky <thomas.lendacky@....com>, "Kalra, Ashish" <ashish.kalra@....com>,
	"Sean Christopherson" <seanjc@...gle.com>, Baoquan He <bhe@...hat.com>,
	<kexec@...ts.infradead.org>, <linux-coco@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv8 17/17] ACPI: tables: Print MULTIPROC_WAKEUP when MADT is
 parsed



On 29/02/2024 4:22 am, Kirill A. Shutemov wrote:
> On Wed, Feb 28, 2024 at 11:08:38AM +1300, Huang, Kai wrote:
>>
>>
>> On 28/02/2024 10:24 am, Kirill A. Shutemov wrote:
>>> When MADT is parsed, print MULTIPROC_WAKEUP information:
>>>
>>> ACPI: MP Wakeup (version[1], mailbox[0x7fffd000], reset[0x7fffe068])
>>>
>>> This debug information will be very helpful during bring up.
>>>
>>> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
>>> Reviewed-by: Baoquan He <bhe@...hat.com>
>>> ---
>>>    drivers/acpi/tables.c | 14 ++++++++++++++
>>>    1 file changed, 14 insertions(+)
>>>
>>> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
>>> index b07f7d091d13..c59a3617bca7 100644
>>> --- a/drivers/acpi/tables.c
>>> +++ b/drivers/acpi/tables.c
>>> @@ -198,6 +198,20 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
>>>    		}
>>>    		break;
>>> +	case ACPI_MADT_TYPE_MULTIPROC_WAKEUP:
>>> +		{
>>> +			struct acpi_madt_multiproc_wakeup *p =
>>> +				(struct acpi_madt_multiproc_wakeup *)header;
>>> +			u64 reset_vector = 0;
>>> +
>>> +			if (p->version >= ACPI_MADT_MP_WAKEUP_VERSION_V1)
>>> +				reset_vector = p->reset_vector;
>>> +
>>> +			pr_debug("MP Wakeup (version[%d], mailbox[%#llx], reset[%#llx])\n",
>>> +				 p->version, p->mailbox_address, reset_vector);
>>> +		}
>>> +		break;
>>> +
>>
>> Hmm.. I hate to say, but maybe it is better to put this patch at some early
>> place in this series w/o mailbox version and reset_vector, and add
>> incremental changes where mailbox/reset_vector is introduced in this series.
>>
>> The advantage is in this way someone can just backport this patch to the old
>> kernel if they care -- this should be part of commit f39642d0dbacd
>> ("x86/acpi/x86/boot: Add multiprocessor wake-up support") anyway.
> 
> It is not subject for backporting. It is just a cosmetics fix (or debug
> facility). Any new MADT type would generate a warning. Nothing wrong with
> it.
> 

OK fine to me.  Thanks.