Re: [PATCHv8 17/17] ACPI: tables: Print MULTIPROC_WAKEUP when MADT is parsed

From: "Huang, Kai" <kai.huang@intel.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>, <x86@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	"Kuppuswamy Sathyanarayanan"
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	"Elena Reshetova" <elena.reshetova@intel.com>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	"Kalra, Ashish" <ashish.kalra@amd.com>,
	"Sean Christopherson" <seanjc@google.com>,
	Baoquan He <bhe@redhat.com>, <kexec@lists.infradead.org>,
	<linux-coco@lists.linux.dev>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv8 17/17] ACPI: tables: Print MULTIPROC_WAKEUP when MADT is parsed
Date: Wed, 28 Feb 2024 11:08:38 +1300	[thread overview]
Message-ID: <0a633c22-8426-42cf-9572-7812ffc75d0a@intel.com> (raw)
In-Reply-To: <20240227212452.3228893-18-kirill.shutemov@linux.intel.com>

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@linux.intel.com>
> Reviewed-by: Baoquan He <bhe@redhat.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.

But I guess nobody really cares since it just prints some dmesg, and 
nobody really noticed this until this series.

So, up to you, and feel free to add:

Acked-by: Kai Huang <kai.huang@intel.com>

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